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In Situ Synchrotron Radiation Techniques: Watching Deformation-induced Structural Evolutions of Polymers
Liang-Bin Li
In press , doi: 10.1007/s10118-018-2169-9
[Abstract](99) [FullText HTML](19) [PDF 1358KB](106)
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Synchrotron radiation (SR) provides highly brilliant light with tunable wavelength from hard X-ray to far infrared, on which scattering, spectroscopy and imaging techniques with high time and spatial resolutions have been developed for in situ study on biological system and materials like polymer. With examples on flow-induced crystallization of polymer, deformation of nanoparticle filler network in rubber composite and necking propagation in tensile stretch, current work attempts to demonstrate the advantages of in situ synchrotron radiation X-ray scattering, X-ray nano-CT and infrared imaging in the study of deformation-induced multi-scale structural evolutions of polymers. With time resolution up to sub-ms, synchrotron radiation is expected to play a great role in understanding non-equilibrium polymer physics under processing and service conditions, while high-throughput characterization platform based on synchrotron radiation opens the possibility to establish polymer Materials Genome database in processing parameter space within reasonable time, which can serve as the roadmap for industrial polymer processing and accelerate material innovation.
CO2-responsive Polymeric Fluorescent Sensor with Ultrafast Response
Yun Wang, Meng Huo, Min Zeng, Lei Liu, Qi-Quan Ye, Xi Chen, Dan Li, Liao Peng, Jin-Ying Yuan
In press , doi: 10.1007/s10118-018-2167-y
[Abstract](61) [FullText HTML](20) [PDF 737KB](8)
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Response speed is one of the most important evaluation criteria for CO2 sensors. In this work, we report an ultrafast CO2 fluorescent sensor based on poly[oligo(ethylene glycol) methyl ether methacrylate]-b-poly[N,N-diethylaminoethyl methacrylate-r-4-(2-methylacryloyloxyethylamino)-7-nitro-2,1,3-benzoxadiazole] [POEGMA-b-P(DEAEMA-r-NBDMA)], in which DEAEMA units act as the CO2-responsive segment and 4-nitrobenzo-2-oxa-1,3-diazole (NBD) is the chromophore. The micelles composed of this copolymer could disassemble in 2 s upon CO2 bubbling, accompanying enhanced fluorescence emission with bathochromic shift. Furthermore, the quantum yield of the NBD chromophore increases with both the CO2 aeration time and the NBD content. Thus we attribute the fluorescent enhancement to the inhibition of the photo-induced electron transfer between unprotonated tertiary amine groups and NBD fluorophores. Though based on " soft” materials, the sensor is durable. These micellar sensors could be facilely recycled by alternative CO2/Ar purging for at least 5 times, indicating good reversibility.
Synergistic Flame-retardant Effect of Epoxy Resin Combined with Phenethyl-bridged DOPO Derivative and Graphene Nanosheets
Wei Yan, Ming-Qiu Zhang, Jie Yu, Sheng-Qiang Nie, Dai-Qin Zhang, Shu-Hao Qin
In press , doi: 10.1007/s10118-017-2175-6
[Abstract](35) [FullText HTML](11) [PDF 1091KB](5)
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Phenethyl-bridged DOPO derivative (DiDOPO) was combined with graphene nanosheets (GNSs) in epoxy resin (EP) to improve its flame retardancy. The results indicated that the introduction of only 1.5 wt% DiDOPO/1.5 wt% GNS in EP increased the limited oxygen index (LOI) from 21.8% to 32.2%, hence meeting UL 94 V-0 rating. The thermogravimetric analyses revealed that char yield rose in presence of GNSs to form thermally stable carbonaceous char. The decomposition and pyrolysis products in gas phase were characterized by thermogravimetry-Fourier transform infrared spectroscopy (TG-FTIR), and release of large amounts of phosphorus were deteceted in the gas phase. The evaluation of flame-retardant effect by cone calorimetry demonstrated that GNSs improved the protective-barrier effect of fire residue of EP/DiDOPO/GNS. The latter was further confirmed by digital photography and scanning electron microscopy (SEM). Also, Raman spectroscopy showed that GNSs enhanced graphitization degree of the resin during combustion. Overall, combination of DiDOPO with GNSs looks an effective way for developing high-performance resins with imporved flame retardancy.
An “In Vivo Self-assembly” Strategy for Constructing Superstructures for Biomedical Applications
Man-Zhu Zhao, Dong-Bing Cheng, Zhao-Ru Shang, Lei Wang, Zeng-Ying Qiao, Jing-Ping Zhang, Hao Wang
In press , doi: 10.1007/s10118-018-2170-3
[Abstract](122) [FullText HTML](20) [PDF 1075KB](10)
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The interfacing study of biopolymer and supramolecular chemistry enables a better understanding of fundamental biochemical processes and the creating of new high-performance biomaterials. In this review, we introduced an " in vivo self-assembly” strategy which means in site construction of functional self-assembled superstructures in specific physiological or pathological conditions in cell, tissue or animal levels that exhibit diverse biomedical effects. By using this strategy, unexpected phenomena and insights, e.g, assembly/aggregation induced retention (AIR) effect have been demonstrated where the self-assembled nanostructures showed extraordinary enhanced accumulation and retention of therapeutics in targeted sites.
Enhancement of Resistance to Protein Fouling of Poly(ether imide) Membrane by Surface Grafting with PEG under Organic Solvent-free Condition
Pattama Phomdum, Sana Gassara, André Deratani, Watchanida Chinpa
In press , doi: 10.1007/s10118-018-2144-5
[Abstract](121) [FullText HTML](81) [PDF 1931KB](42)
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Poly(ether imide) (PEI) membrane with enhanced antifouling property was successfully prepared in a mild and simple procedure. The virgin membrane was firstly functionalized with an aqueous solution of diamino-terminated poly(ethylene oxide) block copolymer (PEG-diamine). Glutaraldehyde was used in a second step as a linker to chemically attach additional PEG-diamine to the primary amine groups grafted on PEI membrane surface. Immobilization of PEG segments was confirmed using Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy and atomic force microscopy. Ultrafiltration experiments revealed that the enhancement of a PEG coverage on the membrane surface provided superior anti-protein-fouling property. Cycles of protein filtration also demonstrated that the antifouling surface was stable over time and excellent ultrafiltration performance could be maintained without the need of harsh cleansing operation.
Tough poly(L-DOPA)-containing Double Network Hydrogel Beads with High Capacity of Dye Adsorption
Pei-Bin Zhang, An-Qi Tang, Zhang-Hui Wang, Jing-Yu Lu, Bao-Ku Zhu, Li-Ping Zhu
In press , doi: 10.1007/s10118-018-2163-2
[Abstract](28) [FullText HTML](16) [PDF 850KB](1)
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Developing a low-cost and well-recyclable adsorbent with high adsorption capacity is greatly desirable in dye wastewater treatment. Here, we demonstrate a kind of novel tough and reusable hydrogel beads with quite high capacity of dye adsorption via incorporating mussel-bioinspired poly(L-DOPA) (PDOPA) into alginate/poly(acrylamide) double network (DN) hydrogels. The synthesized PDOPA nanoaggregates were introduced into the DN hydrogels by simple one-pot mixing with the monomers prior to polymerization. The fabricated hydrogel beads exhibited high mechanical strength and good elastic recovery due to the interpenetrating Ca2+-alginate and poly(acrylamide) networks. It was shown that the beads exhibited relatively high dye adsorption capacity compared to other adsorbents reported in literature, and the introduction of PDOPA with an appropriate amount raised the adsorption capacity. It is believed that the addition of PDOPA and the matrix of double network architecture contributed synergistically to the high adsorption capacity of hydrogel beads. Moreover, the desorption of dyes could be easily realized via rinsing in acidic water and ethanol solution. The hydrogel beads remained the high adsorption capacity even after 5 times of adsorption and desorption cycles. This tough and stable hydrogel with high adsorption capacity may have potential in treatment of dye wastewater released by textile dyeing industry.
Light Electrospun Polyvinylpyrrolidone Blanket for Low Frequencies Sound Absorption
Joshua Avossa, Francesco Branda, Francesco Marulo, Giuseppe Petrone, Stefano Guido, Giovanna Tomaiuolo, Aniello Costantini
In press , doi: 10.1007/s10118-018-2154-3
[Abstract](169) [FullText HTML](57) [PDF 677KB](44)
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Light polymeric soundproofing materials (density = 63 kg/m3) of interest for the transportation industry were fabricated through electrospinning. Blankets of electrospun polyvinylpyrrolidone (average fiber diameter = (1.6 ± 0.5) or (2.8 ± 0.5) µm) were obtained by stacking disks of electrospun mats. The sound absorption coefficients were measured using the impedance tube instrument based on ASTM E1050 and ISO 10534-2. For a given set of disks (from a minimum of 6) the sound absorption coefficient changes with the frequency (in the range 200-1600 Hz) following a bell shape curve with a maximum (where the coefficient is greater than 0.9) that shifts to lower frequencies the higher is the piled disks number and the greater the fiber diameter. This work shows that electrospinning produces sound absorbers with reduced thickness (2-3 cm) and excellent sound absorption properties in the low and medium frequency range.
Carbon Fibers Decorated by Polyelectrolyte Complexes Toward Their Epoxy Resin Composites with High Fire Safety
Xiao-Hui Shi, Li Chen, Bo-Wen Liu, Jia-Wei Long, Ying-Jun Xu, Yu-Zhong Wang
In press , doi: 10.1007/s10118-018-2164-1
[Abstract](74) [FullText HTML](34) [PDF 1309KB](27)
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The achievement of both robust fire-safety and mechanical properties is of vital requirement for carbon fiber (CF) composites. To this end, a facile interfacial strategy for fabricating flame-retardant carbon fibers decorated by bio-based polyelectrolyte complexes (PEC) consisting of chitosan (CH) and ammonium polyphosphate (APP) was developed; and its corresponding fire-retarded epoxy resin composites (EP/(PEC@CF)) without any other additional flame retardants were prepared. The decorated CF’s were characterized by SEM-EDX, XPS and XRD spectra, indicating that the flame-retardant PEC coating was successfully constructed on the surface of CF. Thanks to the nitrogen- and phosphorous-containing PEC, the resulting composites exhibited excellent flame retardancy as the limiting oxygen index (LOI) increased from 31.0% of EP/CF to 40.5% and UL-94 V-0 rating was achieved with only 8.1 wt% PEC. EP/(PEC8.1@CF) also performed well in cone calorimetry with the decrease of peak-heat release rate (PHRR) and smoke production rate (SPR) by 50.0% and 30.4%, respectively, and the value of FIGRA was also reduced to 3.41 kW·m−2·s−1 from 4.84 kW·m−2·s−1, suggesting a considerably enhanced fire safety. Furthermore, SEM images of the burning residues revealed that the PEC coating exhibited the dominant flame-retardant activity in condensed phase via the formation of compact phosphorus-rich char. In addition, the impact strength of the composite was improved, together with no obvious deterioration of flexural properties and glass transition temperature. Taking advantage of the features, the PEC decorated carbon fibers and the relevant composites fabricated by the cost-effective and facile strategy would bring more chances for widespread applications.
Reversible Protein Adsorption on PMOXA/PAA Based Coatings: Role of PAA
Fatima Mumtaz, Chao-Shi Chen, Hai-Kun Zhu, Muhammad Atif, Yan--Mei Wang
In press , doi: 10.1007/s10118-018-2168-x
[Abstract](61) [FullText HTML](29) [PDF 762KB](6)
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In this study we report design of stimuli-responsive coating based on poly(2-methyl-2-oxazoline-random-glycidyl methacrylate) (PMOXA-r-GMA) comb copolymer and poly(acrylic acid)-block-poly(glycidyl methacrylate) (PAA-b-PGMA) block copolymers and scrutinize its ability to control protein adsorption. Firstly, PMOXA/PAA based coatings were prepared by simply spin coating the mixture of PMOXA-r-GMA and PAA-b-PGMA copolymer solutions onto silicon substrates followed by annealing at 110 °C. Then coatings were rigorously characterized by X-ray photoelectron spectroscopy (XPS), the static water contact angle (WCA) test, ellipsometry and atomic force microscopy (AFM) techniques. After that, the relationship of switchable behavior of PMOXA/PAA based coatings with PAA content and chain length was investigated through the change of thickness and WCA upon pH and ionic strength (I) trigger, which indicated that change in thickness and WCA was improved when PAA contents were increased as well as by increasing chain length of PAA in PMOXA/PAA based coatings. Finally, real-time adsorption/desorption of lysozyme (Lyso) on PMOXA/PAA based coatings was monitored using quartz crystal microbalance with dissipation monitoring (QCM-D). The results showed that the Lyso adsorption amount was increased upon increasing chain length and contents of PAA in PMOXA/PAA based coatings. The adsorbed Lyso was then efficiently desorbed by changing pH and I of medium with maximum desorption (> 90% desorption percentage) observed for the suitable ratio of PMOXA and PAA while chain length of PAA was kept longer than that of PMOXA. Furthermore, the prepared coatings were found to repeatedly adsorb and desorb Lyso for four successive cycles of adsorption/desorption which confirmed the stability of prepared coatings.
Effects of Halloysite Nanotube Reinforcement in Expandable Graphite Based Intumescent Fire Retardant Coatings Developed Using Hybrid Epoxy Binder System
Qandeel Fatima Gillani, Faiz Ahmad, M.I. Abdul Mutalib, Puteri S.M. Megat-Yusoff, Sami Ullah
In press , doi: 10.1007/s10118-018-2148-1
[Abstract](50) [FullText HTML](29) [PDF 2567KB](7)
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In this study, the effects of halloysite nanotubes (HNTs) reinforcement in expandable graphite based intumescent fire retardant coatings (IFRCs) developed using a polydimethylsiloxane (PDMS)/phenol BA epoxy system were investigated. Intumescent coating formulations were developed by incorporating different weight percentages of HNTs and PDMS in basic intumescent ingredients (ammonium polyphosphate/melamine/ boric  acid/expandable  graphite, APP/MEL/BA/EG). The performance of intumescent formulations was investigated by furnace fire test, Bunsen burner fire test, field emission electron microscopy (FESEM), thermogravimetric analysis (TGA), transmission electron microscopy (TEM), and Fourier-transform infrared analysis (FTIR). The Bunsen burner fire test results indicated that the fire performance of HNTs and PDMS reinforced intumescent formulation has improved due to the development of silicate network over the char residue. Improved expansion in char residue was also noticed in the formulation, SH(3), due to the minimum decomposition of char carbon. FESEM and TEM results validated the development of silicate network over char layer of coating formulations. A considerable mass loss difference was noticed during thermal gravimetric analysis (TGA) of intumescent coating formulations. Reference formulation, SH(0) with no filler, degraded at 300 °C and lost 50% of its total mass but SH(3), due to synergistic effects between PDMS and HNTs, degraded above 400 °C and showed the maximum thermal stability. XRD analysis showed the development of thermally stable compound mulltie, due to the synergism of HNTs and siloxane during intumescent reactions, which enhanced fire performance. FTIR analysis showed the presence of incorporated siloxane and silicates bonds in char residue, which endorsed the toughness of intumescent char layer produced. Moreover, the synergistic effect of HNTs, PDMS, and other basic intumescent ingredients enhanced the polymer cross-linking in binder system and improved fire resistive performance of coatings.
Amorphous and Crystallizable Thermoplastic Polyureas Synthesized through a One-pot Non-isocyanate Route
Jia-Long Ban, Su-Qing Li, Chen-Feng Yi, Jing-Bo Zhao, Zhi-Yuan Zhang, Jun-Ying Zhang
In press , doi: 10.1007/s10118-018-2165-0
[Abstract](49) [FullText HTML](28) [PDF 1142KB](4)
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A simple one-pot non-isocyanate route for synthesizing thermoplastic polyureas is presented. In situ urethanization was conducted from the ring-opening reaction of ethylene carbonate with poly(propylene glycol) bis(2-aminopropyl ether) and hexanediamine, m-xylylenediamine, or diethylene glycol bis(3-aminopropyl) ether at 100 °C for 6 h under normal pressure. Melt transurethane polycondensation was followed at 170 °C under a reduced pressure of 3 mmHg at different times. A series of non-isocyanate thermoplastic polyureas (NI-TPUreas) were prepared. The NI-TPUreas were characterized by gel permeation chromatography, FTIR, 1H-NMR, differential scanning calorimetry, thermogravimetric analysis, wide-angle X-ray diffraction, atomic force microscopy, and tensile test. NI-TPUreas exhibited Mn of up to 1.67 × 104 g/mol, initial decomposition temperature over 290 °C, and tensile strength of up to 32 MPa. Several crystallizable NI-TPUreas exhibited Tm exceeding 98 °C. NI-TPUreas with good thermal and mechanical properties were prepared through a green and simple one-pot non-isocyanate route.
Dewetting Kinetics of Thin Polymer Films with Different Architectures: Effect of Polymer Adsorption
Li-Na Wang, Huan-Huan Zhang, Lin Xu, Bin-Yuan Liu, Tong-Fei Shi, Shi-Chun Jiang, Li-Jia An
In press , doi: 10.1007/s10118-018-2111-1
[Abstract](251) [FullText HTML](119) [PDF 3207KB](9)
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We have investigated the influence of the adsorption process on the dewetting behavior of the linear polystyrene film (LPS), the 3-arm star polystyrene film (3SPS) and the ring polystyrene film (RPS) on the silanized Si substrate. Results show that the adsorption process greatly influences the dewetting behavior of the thin polymer films. On the silanized Si substrate, the 3SPS chains exhibit stronger adsorption compared with the LPS chains and RPS chains; as a result, the wetting layer forms more easily. For LPS films, with the decrease of annealing temperature, the kinetics of polymer film changes from exponential behavior to slip dewetting. As a comparison, the stability of 3SPS and RPS films switches from slip dewetting to unusual dewetting kinetic behavior. The adsorbed nanodroplets on the solid substrate play an important role in the dewetting kinetics by reducing the driving force of dewetting and increase the resistant force of dewetting. Additionally, Brownian dynamics (BD) simulation shows that the absolute values of adsorption energy (ε) gradually increase from linear polymer (−0.3896) to ring polymer (−0.4033) and to star polymer (−0.4264), which is consistent with the results of our adsorption experiments.
A Soft Shape Memory Reversible Dry Adhesive
Jian-Te Dong, Wei-Ke Zou, Feng Chen, Qian Zhao
In press , doi: 10.1007/s10118-018-2119-6
[Abstract](145) [FullText HTML](114) [PDF 1127KB](17)
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Transfer printing is a critical procedure for manufacturing stretchable electronics. During such a procedure, stamps are utilized to transfer micro devices from silicon wafers to stretchable polymeric substrates. In addition to conventional silicone rubber stamps, epoxy resin based shape memory stamps have been developed and the transfer yield is thus significantly promoted. However, elastic modulus of the epoxy stamps is too high at both glassy and rubbery states, which may break the brittle micro devices during the adhesion process under mechanical pressure. In this work, we synthesized a copolymer of butyl acrylate (BA) and polycaprolactone diacrylate (PCLDA) as a soft reversible dry adhesive enabling a shape memory capability based on crystalline transition of polycaprolactone (PCL) segments. For the sample containing 40 wt% BA and 60 wt% PCLDA, Young’s modulus was 8.3 and 0.9 MPa respectively below and above the thermal transition temperature, which was much lower than that of the epoxy adhesive. On the other hand, the soft material still provided nearly ideal shape memory fixity and recovery ratios. Subsequently, shape memory surface with cone-shaped microstructure was prepared, which enabled a heating induced strong-to-weak adhesion transition when the microstructure recovered from a pressed temporary morphology to the permanent cone-shaped morphology. Such a soft reversible dry adhesive may contribute to large-scale and automated transfer printing processing.
In-line Plasma-induced Graft-copolymerization of Pentaerythritol Triacrylate onto Polypropylene
Gui-Qiu Ma, Guan-Kai Sun, Zhe Ma, Jing-Qing Li, Jing Sheng
In press , doi: 10.1007/s10118-018-2023-0
[Abstract](195) [FullText HTML](124) [PDF 730KB](3)
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Pentaerythritol triacrylate (PETA) was successfully grafted onto the plasma-treated isotactic polypropylene (iPP) via the in situ melt processing. The X-ray photoelectron spectroscopy (XPS) results showed that the hydroxyl and carbonyl groups, and peroxides could be generated via plasma treatment. The content of free radical in plasma-treated iPP (PiPP) was measured by 2,2-diphenyl-1-picrylhydrazyl (DPPH). It was found that the resulting peroxides induced the grafting copolymerization of PETA onto iPP, and the grafted PETA promoted the formation of β-crystal in PiPP, which was evidenced by Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC) and wide-angle X-ray diffraction (WAXD) measurements, respectively.
A Facile Photo-cross-linking Method for Polymer Gate Dielectrics and Their Applications in Fully Solution Processed Low Voltage Organic Field-effect Transistors on Plastic Substrate
Ying Liu, Jia-Qing Zhao, Wen-Jian Sun, Yu-Kun Huang, Su-Jie Chen, Xiao-Jun Guo, Qing Zhang
In press , doi: 10.1007/s10118-018-2110-2
[Abstract](180) [FullText HTML](150) [PDF 1729KB](15)
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A simple and effective photochemical method was developed for cross-linking of polymer gate dielectrics. Laborious synthetic processes for functionalizing polymer dielectrics with photo-cross-linkable groups were avoided. The photo-cross-linker, BBP-4, was added into host polymers by simple solution blending process, which was capable of abstracting hydrogen atoms from polymers containing active C―H groups upon exposure to ultraviolet (UV) radiation. The cross-linking can be completed with a relatively long wavelength UV light (365 nm). The approach has been applied to methacrylate and styrenic polymers such as commercial poly(methylmethacrylate) (PMMA), poly(iso-butylmethacrylate) (PiBMA) and poly(4-methylstyrene) (PMS). The cross-linked networks enhanced dielectric properties and solvent resistance of the thin films. The bottom-gate organic field-effect transistors (OFETs) through all solution processes on plastic substrate were fabricated. The OFET devices showed low voltage operation and steep subthreshold swing at relatively small gate dielectric capacitance.
Multiple Effects Tailoring the Self-organization Behaviors of Triphenylene Side-chain Liquid Crystalline Polymers via Changing the Spacer Length
Xiang-Hui Han, Xi-Wen Yang, Sheng Chen, Hang Luo, Dou Zhang, Hai-Liang Zhang
In press , doi: 10.1007/s10118-018-2108-9
[Abstract](173) [FullText HTML](109) [PDF 9455KB](7)
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Long-alkyl tail triphenylene (TP) side-chain liquid crystalline polymers (SCLCPs) with different spacer length (P-m-TP, m = 2, 3, 4, 6, 8, which is the number of carbon atom in the flexible alkyl spacers) have been successfully synthesized via free radical polymerization. The differential scanning calorimetry (DSC), polarized light microscopy (POM), ultraviolet-visible spectroscopy (UV-Vis), wide-angle X-ray diffraction (WAXD) and small-angle X-ray scattering (SAXS) measurements were performed to investigate the influence of multiple effects on the self-organization behaviors of P-m-TP, including steric effect, decoupling effect and π-π stacking effect. The experimental results revealed that P-m-TP (m = 2, 3, 4) formed the columnar phase which was developed by the TP moieties and the main chain as a whole, suggesting that the side-chains had strong steric effect even though the number of spacer length (m) exceeded 4. In addition, the clearing points (Tis) of the polymers were above 300 °C. When m = 6 and 8, the polymers displayed hexagonal columnar phase and exhibited the low Tis (91 and 80 °C respectively), originating from the self-assembly of triphenylene due to the decoupling effect and π-π stacking effect. This work offers a viable and inspiring pathway to control the phase transition temperature and phase structure of TP SCLCPs via simply tailoring the spacer length and increasing the alkyl tail length of TP.
Effect of a Hybrid Zinc Stearate-Silver System on the Properties of Polylactide and Its Abiotic and the Biotic Degradation and Antimicrobial Activity Thereof
Gabriela Jandíková, Petra Stoplova, Antonio Di Martino, Petr Stloukal, Pavel Kucharczyk, Michal Machovsky, Vladimir Sedlarik
In press , doi: 10.1007/s10118-018-2120-0
[Abstract](161) [FullText HTML](114) [PDF 1670KB](14)
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This work investigates the degradation and properties of a thermoplastically prepared composite comprising a polylactide/ hybrid zinc stearate-silver system. The influence of the zinc stearate-silver system on the properties of the composite is investigated by electron microscopy, differential scanning calorimetry and tensile tests. Furthermore, the antimicrobial activities of the systems are examined. The degradation behaviour of the composites is studied in both abiotic and biotic (composting) environments at an elevated temperature of 58 °C. The results reveal good dispersion of the additive in the PLA matrix, a stabilizing effect exerted by the same on the polylactide matrix during processing, and slight reduction in glass transition temperature. The zinc stearate-silver component also reduces brittleness and extends elongation of the composite. Abiotic hydrolysis is not significantly affected, which is in contrast with pure PLA, although mineralization during the early stage of biodegradation increases noticeably. The composite exhibits antimicrobial activity, even at the lowest dosage of the zinc stearate/silver component (1 wt%). Moreover, Ag and Zn contents were found to be present in the composite during abiotic hydrolysis, which was demonstrated by minimal diffusion of Ag ions from the matrix and very extensive washing of compounds that contained Zn.
Preparation and Properties of Poly(aryl ether sulfone ketone) Ultrafiltration Membrane Containing Fluorene Group for High Temperature Condensed Water Treatment
Xiang-Li Meng, Gen-Hua Yu, Jian Ma
In press , doi: 10.1007/s10118-018-2142-7
[Abstract](96) [FullText HTML](52) [PDF 2228KB](9)
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Novel poly(aryl ether sulfone ketone)s (PAESK) were synthesized from bisphenol A (BPA), 9,9′-bis(4-hydroxyphenyl) fluorene (BHPF), 4,4′-dichlorodiphenylsulfone (DCS) and 4,4′-difluorobenzophenone (DFB) via nucleophilic substitution polymerization, which were subsequently used to fabricate ultrafiltration membrane by phase-inversion method for high temperature condensed water treatment. The obtained high molecular weight co-polymers with fluorene group with good solubility and good thermal stability, can be easily cast into flexible, white and non-transparent flat films. The influence of molar ratio of BPA and BHPF on the properties of the prepared co-polymers and membranes was investigated in detail. SEM study of the morphology of the membranes indicated that the prepared membranes possessed homogeneous pores on the top surface and were sponge-like or finger-like in cross-section. Pure water flux of the membranes increased from 71.87 L·m−2·h−1 to 247.65 L·m−2·h−1, while the retention of BSA decreased slightly, and the water contact angle decreased from 82.1° to 55.6° with the PVP concentration from 0 wt% to 10 wt%. With increasing concentration of PVP, the mechanical properties of membranes decreased, while the thermal stability increased. The permeate flux measurement showed that the PAESK membrane had the potential for high temperature condensed water treatment.
Synthesis and Properties of SEPS-g-PEO Copolymers with Varying Branch Lengths
Zhong-Fu Zhao, Pei-Ying Liu, Chun-Qing Zhang, Wei Liu, Yan-Hui Wang, Tao Tang, Yi-Fu Ding, Yan-Dong Zhang, Fan-Zhi Meng
In press , doi: 10.1007/s10118-018-2104-0
[Abstract](155) [FullText HTML](136) [PDF 4710KB](19)
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Poly(ethylene oxide) (PEO) was controllably grafted from styrene-b-(ethylene-co-propylene)-b-styrene (SEPS) backbones by combining lithiation of styrenic units and living monomer-activated anionic ring-opening polymerization of ethylene oxide (EO) monomers with the aid of co-initiators triisobutyl aluminum. The as-synthesized SEPS-g-PEO copolymers were characterized by SEC, 1H-NMR, FTIR, SAXS, AFM and DSC. When the branch length is relatively small, increase of PEO fraction leads to the increase of the correlation length between neighboring hard domains, but the degree of correlation reduces. When the branch length is relatively large, the phase-separated structures become random both in terms of size and spatial correlation, and macro-phase separated structures appear. The crystallization behavior of the PEO branches can be effectively inhibited in SEPS-g-PEO, so no significant crystallization takes place until the fraction of PEO branches is 20.1 wt%, which greatly promotes the rapid delivery of hydrophilic drugs in the hot-melting pressure-sensitive adhesives (HMPSAs) based on SEPS-g-PEO. Their cumulative release amount of a model drug could achieve 80%, more than twice the value in the HMPSAs based on linear PEO-containing styrenic block copolymers.
Synthesis, Self-assembly and Electrode Application of Mussel-inspired Alternating Copolymers
Ying-Lin Zhang, Chuan-Long Li, Tahir Rasheed, Ping Huang, Yong-Feng Zhou
In press , doi: 10.1007/s10118-018-2151-6
[Abstract](121) [FullText HTML](62) [PDF 1656KB](17)
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We reported the first mussel-inspired alternating copolymer with a high amount of catechol groups (50% molar ratio) through a facile epoxy-amino click reaction between 9,9-bis(4-(2-glycidyloxyethyl)phenyl fluorene (BGEPF) and dopamine (DA). The obtained copolymers were used to prepare carbon/nitrogen-doped α-Fe2O3 nanoparticles through self-assembly, coordination and calcination, which displayed excellent electrochemical performance as anode materials for Li-ion batteries.
Recent Progress in Shape Memory Polymers for Biomedical Applications
Hong-Mei Chen, Lin Wang, Shao-Bing Zhou
In press , doi: 10.1007/s10118-018-2118-7
[Abstract](127) [FullText HTML](91) [PDF 6600KB](12)
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Shape memory polymers (SMPs) as one type of the most important smart materials have attracted increasing attention due to their promising application in the field of biomedicine, textiles, aerospace et al. Following a brief intoduction of the conception and classification of SMPs, this review is focused on the progress of shape memory polymers for biomedical applications. The progress includes the early researches based on thermo-induced SMPs, the improvement of the stimulus, the development of shape recovery ways and the expansion of the applications in biomedical field. In addition, future perspectives of SMPs in the field of biomedicine are also discussed.
Mono- and Binuclear Cobalt(II) Complexes Supported by Quinoline-2-imidate Ligands: Synthesis, Characterization, and 1,3-Butadiene Polymerization
Heng Liu, Rui Zhuang, Bo Dong, Feng Wang, Yan-Ming Hu, Xue-Quan Zhang
In press , doi: 10.1007/s10118-018-2097-8
[Abstract](239) [FullText HTML](121) [PDF 1133KB](12)
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A series of mono- and binuclear Co(II) complexes (Co1Co7) supported by quinoline-2-imidate ligands were synthesized and thoroughly characterized. Measured by single crystal X-ray crystallography, complexes Co1 and Co3 adopted distorted tetrahedral structures around the cobalt center. Upon activation by ethylaluminium sesquichloride (EASC), these cobalt complexes exhibited high catalytic activity and cis-1,4-selectivity towards 1,3-butadiene polymerization. The effects of ligand environment, polymerization temperature, and cocatalyst types on the polymerization were investigated in detail. Interestingly, the binuclear Co(II) complexes exhibited high thermal stability, and the polymer yields were up to 97.2% even at a high temperature of 70 °C.
Origin of Modulus Improvement for Epoxide-terminated Hyperbranched Poly(ether sulphone)/DGEBA/TETA Systems
Xue-Pei Miao, Dao-Jian Cheng, Ya-Dong Dai, Yan Meng, Xiao-Yu Li
In press , doi: 10.1007/s10118-018-2114-y
[Abstract](130) [FullText HTML](109) [PDF 3267KB](5)
Abstract:
It has been experimentally shown that epoxide-terminated hyperbranched polyether sulphone (EHBPES) can significantly improve the mechanical properties of traditional diglycidyl ether of bisphenol A/triethylenetetramine (DGEBA/TETA) systems, but the origin of the improvement is still unclear. In this work, we used molecular dynamics (MD) simulations to gain a thorough understanding of the origin of modulus improvement for EHBPES/DGEBA/TETA systems. It is found that the modulus of EHBPES/DGEBA/TETA systems increases with the increase of EHBPES loading. In addition, the crosslinking density, cohesive energy density (CED), and free volume can be used to understand the modulus for EHBPES/DGEBA/TETA systems. It is shown that the highest modulus is achieved at 7 wt% EHBPES loading due to the highest crosslinking density and CED. When EHBPES loading is below 7 wt%, the higher CED and crosslinking density are responsible for the higher modulus. At higher loadings (> 7 wt%), the decreased modulus is closely related to the decreased crosslinking density and increased fractional free volume. It is expected that our results could be of great implications for designing high-performance epoxy materials.
Core-Corona Structure Formed by Hyaluronic Acid and Poly(L-lysine) via Kinetic Path
Wei Pan, Dong-Xiao Yin, Hai-Rong Jing, Hao-Jing Chang, Hao Wen, De-Hai Liang
In press , doi: 10.1007/s10118-018-2166-z
[Abstract](38) [FullText HTML](27) [PDF 604KB](0)
Abstract:
The structure and kinetics of the complex formed by hyaluronic acid (HA) and poly (L-lysine) (PLL) were studied by time-resolved laser light scattering, TEM, and AFM. Because HA has a hydrophilic backbone, the complexes formed by HA and PLL are different from those formed by oppositely charged polyelectrolytes both having hydrophobic backbones. Instead of forming strong aggregates and even precipitates, the complex in the presence of excess HA is stable in the studied time period. More importantly, the complex spontaneously forms core-corona structure by the rearrangement of HA chains. The core is composed of complex rich of PLL and the corona is mainly HA. Further analysis shows that the hydrogen bond formed by HA creates a barrier hindering the further relaxation of HA chains. The automatic formation of core-corona structure by PLL/HA is helpful not only to understand the relaxation of polyelectrolyte in complex, but also to develop drug carriers with desirable properties.
Improving Damping Properties and Thermal Stability of Epoxy/Polyurethane Grafted Copolymer by Adding Glycidyl POSS
Ge-Liang Zhu, Di Han, Ye Yuan, Feng Chen, Qiang Fu
In press , doi: 10.1007/s10118-018-2145-4
[Abstract](88) [FullText HTML](39) [PDF 721KB](4)
Abstract:
Modified castor oil-based epoxy resin (EP)/polyurethane (PU) grafted copolymer by glycidyl polyhedral oligomeric silsesquioxane (glycidyl POSS) was synthesized. The damping properties, thermal stability, mechanical properties and morphology of the grafted copolymer modified by glycidyl POSS were studied systematically. The results revealed that the incorporation of glycidyl POSS improved the damping performance evidently and broadened damping temperature range, especially when the glycidyl POSS content was 0.2%–1%. At the same time, there was a slight increase in thermal stability with the increase of POSS content. The tensile properties changed with the change of the copolymer’sTg, decreased at low POSS contents and increased at high POSS contents. This modified copolymer has the potential to be used as film damping material or constrained damping layer.
Preparation of Polylactide Composite with Excellent Flame Retardance and Improved Mechanical Properties
Chu-Bo Sun, Hong-Da Mao, Feng Chen, Qiang Fu
In press , doi: 10.1007/s10118-018-2150-7
[Abstract](46) [FullText HTML](31) [PDF 749KB](1)
Abstract:
Despite the good biodegradable and mechanical properties, poly(lactic acid) still suffers from a highly inherent flammability, which restricts its applications in the electric and automobile fields. In order to improve the flame retardancy of PLA, in this work, melamine polyphosphate (MPP) and zinc bisdiethylphosphinate (ZnPi) were firstly incorporated into PLA, and the synergistic effect of them on flame retardance of PLA was investigated using limiting oxygen index (LOI), UL-94 vertical measurement, scanning electron microscopy (SEM) and cone calorimeter tests etc. The results showed that PLA composite with 15 wt% of MPP/ZnPi (3:2) had the best flame-retardant efficiency with LOI value of 30.1 and V-0 rating in UL-94 tests, which was far better than using MPP or ZnPi alone. What is more, although a wide range of flame retardants have been developed to reduce the flammability, so far, they normally compromise the mechanical properties of PLA. On the premise of maintaining good flame-retardant performance, we improved the toughness of flame-retardant PLA composite, and the impact strength of flame-retardant PLA composite was more than tripled (8.08 kJ/m2) by adding thermoplastic urethanes (TPU). This work offers an innovative method for the design of the unique integration of extraordinary flame retardancy and toughening reinforcement for PLA materials.
ε-Poly(L-lysine)-based Hydrogels with Fast-acting and Prolonged Antibacterial Activities
Yi-Jie Zou, Shi-Sheng He, Jian-Zhong Du
In press , doi: 10.1007/s10118-018-2156-1
[Abstract](139) [FullText HTML](37) [PDF 1162KB](5)
Abstract:
Bacterial infections and the associated morbidity and mortality due to bacterial pathogens in wounds and medical implants have been increasing as most of current coatings cannot fulfill all the requirements including excellent intrinsically antibacterial activity, low cytotoxicity, and favorable physical properties. Herein, we present a kind of antibacterial hydrogel based on ε-poly(L-lysine) (EPL) grafted carboxymethyl chitosan (CMC-g-EPL) as the inherently antibacterial matrix and the surplus EPL as highly efficient antimicrobial agent. Such hydrogels possess tunable swelling abilities with water absorption percentages of 800%–2000% and modulus varying from 10 kPa to 100 kPa, and exhibit two-stage excellent antibacterial behavior. First, the free EPL can be released from the hydrogel network for quick and highly efficient bacteria killing with 99.99% of efficacy; second, the grafted EPL endows hydrogel matrix with prolonged intrinsically antibacterial activity, especially when most of free EPL is released from the hydrogel. Overall, we provide a new insight for preparing highly effective antibacterial hydrogels.
Toughening Poly(lactic acid) with Imidazolium-based Elastomeric Ionomers
Lu Chen, Kuan Hu, Si-Ting Sun, Hai Jiang, Dong Huang, Kun-Yu Zhang, Li Pan, Yue-Sheng Li
In press , doi: 10.1007/s10118-018-2143-6
[Abstract](97) [FullText HTML](45) [PDF 1324KB](4)
Abstract:
Imidazolium-based elastomeric ionomers (i-BIIR) were facilely synthesized by ionically modified brominated poly(isobutylene-co-isoprene) (BIIR) with different alkyl chain imidazole and thoroughly explored as novel toughening agents for poly(lactic acid) (PLA). The miscibility, thermal behavior, phase morphology and mechanical property of ionomers and blends were investigated through dynamic mechanical analyses (DMA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM), tensile and impact testing. DMA and SEM results showed that better compatibility between the PLA and i-BIIR was achieved compared to the PLA/unmodified BIIR elastomer. A remarkable improvement in ductility with an optimum elongation at break up to 235% was achieved for the PLA/i-BIIR blends with 1-dodecylimidazole alkyl chain (i-BIIR-12), more than 10 times higher than that of pure PLA. The impact strengths of PLA were enhanced from 1.9 kJ/m2 to 4.1 kJ/m2 for the PLA/10 wt% i-BIIR-12 blend. Toughening mechanism had been established by systematical analysis of the compatibility, intermolecular interaction and phase structures of the blends. Interfacial cavitations initiated massive shear yielding of the PLA matrix owing to a suitable interfacial adhesion which played a key role in the enormous toughening effect in these blends. We believed that introducing imidazolium group into the BIIR elastomer was vital for the formation of a suitable interfacial adhesion.
Enolic Schiff Base Zinc Amide Complexes: Highly Active Catalysts for Ring-Opening Polymerization of Lactide and ε-Caprolactone
Chen-Yang Hu, Ran-Long Duan, Jing-Wei Yang, Shu-Jun Dong, Zhi-Qiang Sun, Xuan Pang, Xian-Hong Wang, Xue-Si Chen
In press , doi: 10.1007/s10118-018-2129-4
[Abstract](147) [FullText HTML](134) [PDF 523KB](3)
Abstract:
A series of zinc silylamido complexes based upon NNO tridentate enolic Schiff base framework have been synthesized and characterized. These complexes were tested for the ring opening polymerization of lactide and ε-caprolactone, exhibiting notably high activity at ambient temperature. The influence of imine bridge length and substituents of diketone over the course of polymerization was investigated in details. Remarkably, 4a was confirmed to be a rare example of exceedingly active and robust zinc catalysts, achieving major transformation of lactide under extremely low loading (0.025 mol%) within 18 min. The influence of various monomers as well as the polymerization mechanism have also been discussed.
Multifunctional Nanoplatform Based on pH-responsive Micelle Coated with Discontinuous Gold Shell for Cancer Photothermo-chemotherapy and Photoacoustic Tomography
Yi Huang, Xiao-Xia Li, Lu Zhang, Xiao-Yan Chen, Cheng-Bo Liu, Jing-Qin Chen, Yong Wang, Xin-Tao Shuai
In press , doi: 10.1007/s10118-018-2141-8
[Abstract](147) [FullText HTML](46) [PDF 2789KB](26)
Abstract:
Photothermo-chemotherapy, as a new strategy for cancer treatment, incorporates the complementary advantages of photothermal therapy and chemotherapy. In this study, a pH-sensitive diblock copolymer poly(aspartic acid-butanediamine)-poly(2-(diisopropylamino)ethyl methacrylate) (PAsp(DAB)-PDPA) was synthesized and self-assembled into doxorubicin-loaded micelle, which was further used as a template to form a gold nanoshell. After further modification with poly(ethylene glycol), the resulting nanoplatform provided good biocompatibility and desirable photo-thermal conversion efficiency to facilitate photothermal therapy. Meanwhile the nanoparticle also exhibited pH sensitivity, which prevented drug loss while circulating in the blood but enabled rapid drug release after endocytosis. An improved effect was achieved with the combination of photothermal therapy and chemotherapy. In addition, systemic delivery of the nanoplatform could be monitored by photoacoustic tomography. Thereby, this multifunctional nanoplatform would be highly potential for the diagnosis and therapy of cancer.
Preparation of Polylactide/Poly(ether)urethane Blends with Excellent Electro-actuated Shape Memory via Incorporating Carbon Black and Carbon Nanotubes Hybrids Fillers
Yuan Wei, Rui Huang, Peng Dong, Xiao-Dong Qi, Qiang Fu
In press , doi: 10.1007/s10118-018-2138-3
[Abstract](136) [FullText HTML](57) [PDF 3355KB](7)
Abstract:
In this work, hybrid conductive fillers of carbon black (CB) and carbon nanotubes (CNTs) were introduced into polylactide (PLA)/thermoplastic poly(ether)urethane (TPU) blend (70/30 by weight) to tune the phase morphology and realize rapid electrically actuated shape memory effect (SME). Particularly, the dispersion of conductive fillers, the phase morphology, the electrical conductivities and the shape memory properties of the composites containing CB or CB/CNTs were comparatively investigated. The results suggested that both CB and CNTs were selectively localized in TPU phase, and induced the morphological change from the sea-island structure to the co-continuous structure. The presence of CNTs resulted in a denser CB/CNTs network, which enhanced the continuity of TPU phase. Because the formed continuous TPU phase provided stronger recovery driving force, the PLA/TPU/CB/CNTs composites showed better shape recovery properties compared with the PLA/TPU/CB composites at the same CB content. Moreover, the CB and CNTs exerted a synergistic effect on enhancing the electrical conductivities of the composites. As a result, the prepared composites exhibited excellent electrically actuated SME and the shape recovery speed was also greatly enhanced. This work demonstrated a promising strategy to achieve rapid electrically actuated SME via the addition of hybrid nanoparticles with self-networking ability in binary PLA/TPU blends over a much larger composition range.
Effect of Halogen Chain End Fidelity on the Synthesis of Poly(methyl methacrylate-b-styrene) by ATRP
Guang-Cheng Huang, Sheng-Xiang Ji
In press , doi: 10.1007/s10118-018-2139-2
[Abstract](160) [FullText HTML](73) [PDF 605KB](12)
Abstract:
Poly(methyl methacrylate-b-styrene) (PMMA-b-PS) block copolymers are synthesized by two consecutive ATRPs and fractionated into four fractions. The halogen chain end fidelity (CEF) in PMMA-b-PS is quantified based on the analysis of each fraction. Compared to ethyl 2-phenyl-2-bromoacetate/CuBr/2,2′-bipyridine (EPBA/CuBr/bpy) and CuBr/N,N,N′,N″,N″-pentamethyldiethylene-triamine (CuBr/PMDETA) catalysts, PMMA-b-PS synthesized using p-toluenesulfonyl chloride/CuCl/bpy (TsCl/CuCl/bpy) and CuCl/PMDETA catalysts has a higher halogen CEF and a better control on molecular weight.
Synthesis of Poly(isosorbide carbonate) via Melt Polycondensation Catalyzed by Ca/SBA-15 Solid Base
Xiao-Long Shen, Zi-Qing Wang, Qing-Yin Wang, Shao-Ying Liu, Gong-Ying Wang
In press , doi: 10.1007/s10118-018-2137-4
[Abstract](157) [FullText HTML](103) [PDF 1542KB](30)
Abstract:
Ca/SBA-15 solid bases with different Ca/Si atomic ratios were prepared by a one-pot route and employed as catalysts for the production of poly(isosorbide carbonate) (PIC) from diphenyl carbonate and isosorbide via a transesterification polymerization process. The relationship between physicochemical properties and catalytic performance for Ca/SBA-15 in this melt process was investigated by means of various characterization techniques. It was found that basic site amount and strength were responsible for this transesterification process; the weak and medium basic sites inclined to promote polycondensation reaction. It was worth noting that strong basic sites could favor the decomposition of the resultant PIC, resulting in the decrease of weight-average molecular weight (Mw) and yield, and the sample with Ca/Si atomic ratio of 0.4 exhibited the best catalytic performance, giving PIC with Mw of 4.88 × 104 g/mol and Tg of 169 °C at the optimal conditions. This excellent activity can be ascribed to the presence of rich basic sites and specific basic strength on the surface of 0.4Ca/SBA-15.
Largely Improved Stretch Ductility and β-Form Room-temperature Durability of Poly(vinylidene fluoride) by Incorporating Aliphatic Polyketone
Shui-Qin Pu, Shuo Guo, Ke Wang, Qiang Fu
In press , doi: 10.1007/s10118-018-2134-7
[Abstract](145) [FullText HTML](105) [PDF 2190KB](7)
Abstract:
In this study, we attempt to prepare a new blending system of poly(vinylidene fluoride) (PVDF) and aliphatic polyketone (POK) by melt compounding. The latter is a promising engineering plastic with comprehensive mechanical performances. When POK acted as minor phase to homogeneously disperse in and intimately contact with PVDF matrix, the brittle tensile behavior of neat PVDF transferred into a remarkably flexible manner (the elongation at break increased for 20 times), and more interestingly, the room-temperature durability of β-form PVDF in the uniaxially drawn blend film was obviously better than that in the neat PVDF film. Fourier transform infrared spectroscopy revealed that specific dipole interaction existed between CF2 group of PVDF and C=O group of POK. The intermolecular dipolar interaction induced good compatibility in the PVDF/POK blends, as evidently proved by fine two-phase morphology and decreased melting points of POK crystals. Therefore, the good compatibility and interfacial enhancement are responsible for the improvement of the stretch ductility and β-form room-temperature durability of the PVDF/POK blends.
Effect of Linear and Ring-like Co-units on the Temperature Dependence of Nucleation and Growth in II-I Phase Transition of Butene-1 Copolymers
Ya-Hui Lou, Yi-Long Liao, Li Pan, Bin Wang, Yue-Sheng Li, Zhe Ma
In press , doi: 10.1007/s10118-018-2135-6
[Abstract](130) [FullText HTML](66) [PDF 667KB](7)
Abstract:
The phase transition from tetragonal form II to hexagonal form I was studied for the butene-1/ethylene and butene-1/1,5-hexadiene random copolymers, which have comparable molecular weight but distinct linear ethylene and ringlike methylene-1,3-cyclopentane (MCP) structural co-units, respectively. It is known that this solid phase transition follows the nucleation-growth mechanism, so the stepwise annealing protocol was utilized to investigate the influences of co-units on the optimal nucleation and growth temperatures. Compared with optimal nucleation and growth temperatures of −10 and 35 °C, respectively, in polybutene-1 homopolymer, two butene-1/ethylene copolymers with 1.5 mol% and 4.3 mol% co-units have the slightly lower optimal nucleation temperature of −15 °C but much higher optimal growth temperature of 50 °C. Clearly, the effect of ethylene co-unit is more significant on varying optimal temperature for growth than for nucleation. Furthermore, when the incorporated co-unit is ringlike MCP, the optimal nucleation temperature is −15 °C for 2.15 mol% co-units, the same with above BE copolymers, but −13 °C for a very low concentration of 0.65 mol%. Interestingly, the optimal growth temperature of butene-1/1,5-hexadiene copolymers with 0.65 mol%−2.15 mol% MCP co-units increases to 55 °C, which is also independent on co-unit concentration. These obtained values of optimal temperatures provide crucial parameters for rapid II-I phase transition.
Establishment of Constitutive Model of Silicone Rubber Foams Based on Statistical Theory of Rubber Elasticity
Cheng-Sha Wei, Ai Lu, Su-Ming Sun, Xing-Wen Wei, Xiao-Yu Zhou, Jie Sun
In press , doi: 10.1007/s10118-018-2125-8
[Abstract](158) [FullText HTML](104) [PDF 623KB](5)
Abstract:
In this study, a constitutive model based on microscopic physical mechanism of silicone rubber foams was established. A theoretical statistical model of rubber elasticity considering the effect of dangling chains was modified to build this model. When a strain amplification factor (X) was introduced, the theoretical model could fit the tensile stress-strain data of mono- and bi-modal foam matrix well (Adj. R-Square = 0.9989, 0.9983). Parameters related to the polymer network, namely, average molecular weight (Mc) and volume fraction (ϕ) of chain segments between adjacent cross-linking points (network strands), were calculated by probabilistic method from the number-average molecular weight (Mn), vinyl content (wVi) of the primary polysiloxanes and percent conversion (q) of vinyl groups. The primary and infinite strain amplification factors (X0, X) and decay exponent (z), introduced by X and related to the nanoparticles, were obtained by fitting. Inspired by the fact that the actual strain of matrix was lower than that of the foams’, we introduced another item, strain hysteresis item (H, related with the foam porosity and cell structure), into the statistical model as well. With the same above values of Mc, ϕ, X0 and X, the model could also fit the compressive stress-strain data of mono- and bi-modal foams well (Adj. R-Square = 0.9948, 0.9985). Interestingly, the strain hysteresis items of the mono- and bi-modal foams almost completely coincided under all experimental strains, which may be attributed to the almost equal porosity and similar cell structure of the two foams. This constitutive model may connect the macroscopic stress-strain behaviour to the parameters of microscopic molecular structures, promisingly providing a basis for the performance improvement and optimization of silicone rubber foams.
The Silk Textile Embedded in Silk Fibroin Composite: Preparation and Properties
Yu Duan, Xin Chen, Zheng-Zhong Shao
In press , doi: 10.1007/s10118-018-2117-8
[Abstract](148) [FullText HTML](127) [PDF 1097KB](4)
Abstract:
Silk reinforced silk-fibroin-based composites were prepared by embedding of silk textile into regenerated silk fibroin (RSF) matrix. The breaking stress and breaking strain of the composites were found 37.7 MPa and 71.1% respectively at (95 ± 5)% RH. Morphological analysis was carried out to observe fracture behavior of the samples. The in vitro biodegradation test showed that the composite degraded slowly and lost 70% weight at the end of 168 h. Moreover, compared with RSF pure film, the composite kept strength and toughness much longer time. In conclusion, this composite has the potential for more accurate cytology research and biomedical tests in the future.
Bioinspired Water-soluble Polymers with Grafted Polyamine Chains: Synthesis and Complexation with Oligonucleotides
Vadim V. Annenkov, Uma Maheswari Krishnan, Viktor A. Pal'shin, Stanislav N. Zelinskiy, Gayathri Kandasamy, Elena N. Danilovtseva
In press , doi: 10.1007/s10118-018-2133-8
[Abstract](171) [FullText HTML](91) [PDF 1982KB](6)
Abstract:
The siliceous frustules of diatom algae contain complex proteins known as silaffins, which consist of a peptide chain with grafted polyamine chains. These polyamines contain twenty or more nitrogen atoms with trimethylene groups between the nitrogens. We synthesized a set of polymers containing grafted long-chain polyamine fragments by using acryloyl chloride (ACh) polymers and activated acrylic acid copolymers as the starting materials. The new polymers contained 0.05 mol%−3.2 mol% of polyamine chains, which corresponded to 0.06−3.56 mmol·g−1 amine groups. The new amine-containing polymers formed complexes with short (19-21-mer) deoxyribonucleic acid (DNA) and ribonucleic acid (RNA) strands, and these complexes penetrated into model yeast cells and A549 lung cancer cell. This study demonstrates the potential of these species based on long-chain polyamines to serve as novel gene delivery systems.
Effects of Binding Energy of Bioinspired Sacrificial Bond on Mechanical Performance of cis-1,4-Polyisoprene with Dual-crosslink
Sheng Wang, Zheng-Hai Tang, Jing Huang, Bao-Chun Guo
In press , doi: 10.1007/s10118-018-2131-x
[Abstract](203) [FullText HTML](103) [PDF 1053KB](17)
Abstract:
Although bioinspired sacrificial bonds have been demonstrated to be efficient in improving the mechanical properties of polymer materials, the effect of binding energy of a specific dynamic bond on the ultimate mechanical performance of a polymer network with dual-crosslink remains unclear. In this contribution, diamine and sulfur curing package are introduced simultaneously into a sulfonated cis-1,4-polyisoprene to create dually-crosslinked cis-1,4-polyisoprene network with sulfonate-aminium ionic bonds as the sacrificial bonds. Three diamines (primary, secondary and tertiary) with the same spacer between the two nitrogen atoms are used to create the ionic bonds with different binding energies. Although the binding energy of ionic bond does not affect the glass transition temperature of cis-1,4-polyisoprene (IR), it exerts definite influences on strain-induced crystallization and mechanical performance. The capabilities of diamine in dissipating energy, promoting strain-induced crystallization and enhancing the mechanical performance are in the same order of secondary diamine > primary diamine > tertiary diamine. The variations in mechanical performances are correlated to the binding energy of the ionic bond, which is determined by p Ka values.
Slight Structural Disorder in Bithiophene-based Random Terpolymers with Improved Power Conversion Efficiency for Polymer Solar Cells
Meng-Han Wang, Zhong-Yuan Xue, Zhi-Wei Wang, Wei-Hua Ning, Yu Zhong, Ya-Nan Liu, Chun-Feng Zhang, Sven Huettner, You-Tian Tao
In press , doi: 10.1007/s10118-018-2128-5
[Abstract](150) [FullText HTML](112) [PDF 1821KB](3)
Abstract:
A series of random terpolymers P2P5 were designed and synthesized by randomly embedding 5 mol%, 10 mol%, 15 mol% and 25 mol% feed ratios of low cost 2,2-bithiophene as the third monomer to the famous donor-acceptor (D-A) type copolymer PTB7-Th (P1). All polymers showed similar molecular weight with number-average molecular weight (Mn) and weight-average molecular weight (Mw) in the range of (59−74) and (93−114) kg·mol−1, respectively, to ensure a fair comparison on the structure-property relationships. Compared with the control copolymer PTB7-Th, the random terpolymers exhibited enhanced absorption intensity in a wide range from 400 nm to 650 nm in both solution and film as well as in polymer/PC71BM blends. From grazing incident wide-angle X-ray diffraction (GIWAXS), compared with the regularly alternated copolymer PTB7-Th, the random terpolymers demonstrated mild structural disorder with reduced (100) lamellar stacking and slightly weakened (010) π-π stacking for the polymers as well as slightly reduced PC71BM aggregation in polymer/PC71BM blends. However, the measured hole mobility for terpolymers ((1.20−3.73) × 10−4 cm2·V−1·s−1) was evaluated to be comparable or even higher than 1.35 × 10−4 cm2·V−1·s−1 of the alternative copolymer. Enhanced average power conversion efficiency (PCE) from 7.35% to 8.11% and 7.79% to 8.37% was observed in both conventional and inverted device architectures from copolymer P1 to terpolymers P4, while further increasing the 2,2-bithiophene feed ratio decreased the PCE.
Massive Preparation of Coumarone-indene Resin-based Hyper-crosslinked Polymers for Gas Adsorption
Ke Tian, Ting-Ting Zhu, Ping Lan, Zheng-Chen Wu, Wei Hu, Fei-Fei Xie, Lei Li
In press , doi: 10.1007/s10118-018-2127-6
[Abstract](171) [FullText HTML](107) [PDF 1395KB](11)
Abstract:
Hyper-crosslinked polymers (HCPs) are promising materials for gas capture and storage because of their low cost and easy preparation. In this work, we report the massive preparation of coumarone-indene resin-based hyper-crosslinked polymers via one-step Friedel-Crafts alkylation. Low-cost coumarone-indene resin serves as the new building block and chloroform is employed as both solvent and external crosslinker. A maximum surface area of 966 m2·g−1 is achieved, which is comparable with that of previously-reported coal tar-based porous organic polymers. Most importantly, a large number of heteroatoms including inherent oxygen atoms and introduced chlorine atoms in obtianed HCPs further enhance the interaction between specific sorbate molecule and adsorbent. Therefore, optimal structural and chemical property endow the new coumarone-indene resin-based HCPs with decent gas storage capacity (14.60 wt% at 273 K and 0.1 MPa for CO2; 1.18 wt% at 77.3 K and 0.1 MPa for H2). These results demonstrate that new HCPs are potential candidates for applications in CO2 and H2 capture.
Diffusion and Relaxation Dynamics of Supercooled Polymer Melts
Deng Pan, Zhao-Yan Sun
In press , doi: 10.1007/s10118-018-2132-9
[Abstract](154) [FullText HTML](113) [PDF 1412KB](8)
Abstract:
The dynamic properties of polymer melts are investigated in the range of normal liquid regime to the supercooled liquid regime. The polymer is modeled as a coarse-grained bead-spring model with chain length ranging from 5 to 160. The mean squared displacement and non-Gaussian parameter are used to describe the self diffusion of polymer beads. We find slow dynamics with decreasing temperature and increasing chain length. The time evolution of non-Gaussian parameters shows two peaks (or one peak one shoulder) in the α-relaxation time, τα, regime and sub-diffusion time regime, respectively, where the first primary peak indicates the dynamic heterogeneity stemmed from the motion of beads, and the secondary peak is the result of correlated motion along a polymer chain. Moreover, the relaxation of polymer beads shows clear two-step decay in supercooled melts and the dynamics shows growing heterogeneity with decreasing temperature. As chain length is increased, a peak of the dynamic susceptibility occurs, and the peak height, \begin{document}${\textit{χ}}_4^*$\end{document} , increases and then reaches a plateau. The curves of the height of the first peak of \begin{document}${\textit{α}}_2^{}$\end{document} , \begin{document}${\textit{α}}_2^*$\end{document} , versus τα and the curves of \begin{document}${\textit{χ}}_4^*$\end{document} versus τα follow two master curves for different chain lengths. Our results indicate the similarity of dynamic heterogeneity dominated by the motion of single bead even the chain length is different. It is interesting to find that the Stokes-Einstein (SE) relation between τq and diffusion coefficient D, \begin{document}$ D \sim {\textit{τ}}_{q}^{-1}$\end{document} , is highly length-scale dependent. The SE relation breaks down in both normal melts regime and supercooled regime at large magnitude of wave vectors, attributed to the non-Brownian motion arising from the chain connectivity and growing heterogeneity due to supercooling. However, the SE relation is reconstructed when the probing length scale is large (at small magnitude of wave vectors). Our results show a hierarchical physical picture of the supercooled polymeric dynamics.
Liquid-crystal Assembly of Semiflexible-coil/Homopolymer Blends: a Dissipative Particle Dynamics Study
Yan-Yan Wang, Qing-Liang Song, Lin-Li He
In press , doi: 10.1007/s10118-018-2122-y
[Abstract](147) [FullText HTML](104) [PDF 2224KB](4)
Abstract:
The liquid-crystal assembly of semiflexible-coil diblock copolymers with coil or semiflexible homopolymers is studied by dissipative particle dynamics simulation. Phase diagrams of the blends and orientation ordering parameters among semiflexible blocks are constructed as a function of chain stiffness and homopolymer volume fraction. For semiflexible-coil/coil blends with varying stiffness of semiflexible blocks, we display the rich phase behaviors of the system transited from coil-coil/coil to rod-coil/coil blends. The disorder-lamellae or lamellae-liquid crystalline transition and " dry brush” phenomenon induced by coil homopolymers are observed. For semiflexible-coil/semiflexible blends, adding semiflexible homopolymers also leads to a disorder-order transition and even a transition between monolayer and bilayer smectic-A phase. The results demonstrate that blending homopolymers into semiflexible copolymers can induce liquid-crystal assembly and even improve the orientation ordering of semiflexible blocks effectively.
NMR Analysis to Identify Biuret Groups in Common Polyureas
Wei-Guang Qiu, Fei-Long Zhang, Xu-Bao Jiang, Xiang-Zheng Kong
In press , doi: 10.1007/s10118-018-2130-y
[Abstract](230) [FullText HTML](108) [PDF 773KB](18)
Abstract:
Polyureas (PU) are well known as a class of high impact engineering materials, and widely used also in emerging advanced applications. As a general observation, most of them are only soluble in a very limited number of highly protonic solvents, which makes their chemical structure analysis a great challenge. Besides the presence of abundant hydrogen bonding, the poor solubility of PU in common organic solvents is often ascribed to the formation of biuret crosslinking in their molecular chains. To clarify the presence of biuret groups in PU has been of great interest. To this end, two samples, based on hexamethylene diisocyanate (HDI) and toluene diisocyanate (TDI) respectively, were synthesized by precipitation polymerization of each of these diisocyanates in water-acetone at 30 °C. Their chemical structures were analyzed by high resolution magic angle spinning (HR-MAS) NMR, and through comparison of their NMR spectra with those of specially prepared biuret-containing polyurea oligomers, it was concluded that biuret group was absent in all the PU prepared at 30 °C. In addition, this NMR analysis was also applied to a PU obtained by copolymerization of TDI with ethylene diamine (EDA) and water at 65 °C in EDA aqueous solution. It was confirmed that biuret unit was also absent in this PU and that EDA was more active than water towards TDI. The presence of EDA was crucial to the formation of uniform PU microspheres. This study provides therefore a reliable method for the analysis of PU chemical structure.
Synthesis of Water-soluble, Polyester-based Dendrimer Prodrugs for Exploiting Therapeutic Properties of Two Triterpenoid Acids
Silvana Alfei, Gaby Brice Taptue, Silvia Catena, Angela Bisio
In press , doi: 10.1007/s10118-018-2124-9
[Abstract](155) [FullText HTML](110) [PDF 790KB](4)
Abstract:
Dendrimers are macromolecules characterized by high controlled size, shape and architecture, presence of inner cavities able to accommodate small molecules and many peripheral functional groups to bind target entities. They are of eminent interest for biomedical applications, including gene transfection, tissue engineering, imaging, and drug delivery. The well-known pharmacological activities of ursolic and oleanolic acids are limited by their small water solubility, non-specific cell distribution, low bioavailability, poor pharmacokinetics, and their direct administration could result in the release of thrombi. To overcome such problems, in this paper we described their physical incorporation inside amino acids-modified polyester-based dendrimers which made them highly water-soluble. IR, NMR, zeta potential, mean size of particles, buffer capacity and drug release profiles of prepared materials were reported. The achieved water-soluble complexes harmonize a polycationic character and a buffer capacity which presuppose efficient cell penetration and increased residence time with a biodegradable cell respectful scaffold, thus appearing as a promising team of not toxic prodrugs for safe administration of ursolic and oleanolic acids.
Initiation, Development and Stabilization of Cavities during Tensile Deformation of Semicrystalline Polymers
Ying Lu, Yong-Feng Men
In press , doi: 10.1007/s10118-018-2123-x
[Abstract](153) [FullText HTML](99) [PDF 948KB](5)
Abstract:
By using polybutene-1 as a typical example, we illustrate the initiation, development and stabilization of cavities in the sample during tensile deformation. Samples with the same crystallinity, long spacing and crystalline lamellar thickness but very different sizes of spherulites were prepared via changing the melt history. Dimension of cavities during stretching the samples was determined by in situ ultra small angle X-ray scattering techniques. It turned out that the size of the cavities was bigger in the sample with larger spherulites than the one with smaller spherulites. The results show clear evidence of initiating cavities within crystalline phase at the grain-boundary of crystalline blocks, growing of cavities passing through parallel stacked lamellar crystals and amorphous layers and finally stablized by tilted lamellae at both ends of the plate-like cavities within the spherulites.
Phase Separation, Wetting and Dewetting in PS/PVME Blend Thin Films: Dependence on Film Thickness and Composition Ratio
Tian Xia, Ya-Ping Qin, Ting Huang
In press , doi: 10.1007/s10118-018-2121-z
[Abstract](196) [FullText HTML](108) [PDF 3117KB](8)
Abstract:
The effects of film thickness and composition ratio on the morphology evolution of polystyrene (PS)/poly(vinyl methyl ether) (PVME) blend thin films were investigated. Diverse morphology evolutions including droplet-matrix structure, hole emergence, bicontinuous structure formation, percolation-to-droplet transition could be observed under annealing in two-phase region, depending on film thickness and composition ratio. The mechanism for these morphology variations was related to the complex effects of phase separation, dewetting and preferential wetting. The comparison between the thickness of bottom PVME layer and the twice of gyration radius 2Rg(PVME) played a dominant role in morphology control. Only when the PS/PVME film had specific film thickness and compositional symmetry, phase separation and dewetting could happen in sequence.
Synthesis of Highly Regioregular, Head-to-Tail Coupled Poly(3-octylesterthiophene) via C―H/C―H Coupling Polycondensation
Qiang Zhang, Yue-Feng Li, Lu-Di Deng, Lin-Lin Zhao, Chen-Xi Li, Yan Lu
In press , doi: 10.1007/s10118-018-2116-9
[Abstract](172) [FullText HTML](108) [PDF 667KB](5)
Abstract:
Highly regioregular, head-to-tail coupled poly(3-octylesterthiophene) was synthesized by the Pd-catalysed oxidative C―H/C―H coupling polycondensation. The regioregularity of polymer products was confirmed by the 1H-NMR technique. Furthermore, the effects of various reaction factors including polymerization temperature, solvents and catalysts etc. on the yield, molecular weight and structural regioregularity of the resultant polymers were systematically studied. The optical, electrochemical and crystallization properties of the resultant P3OET with different HT regioregularities in solution and film state were studied by UV-Vis and fluorescent spectroscopy, cyclic voltammetry and X-ray diffraction (XRD), resepectively.
Dewetting Behavior of Hydrogen Bonded Polymer Complex Film under Hydrothermal Condition
Chao Su, Song-mei Ma, Geng-xin Liu, Shu-guang Yang
In press , doi: 10.1007/s10118-018-2109-8
[Abstract](192) [FullText HTML](117) [PDF 2890KB](2)
Abstract:
Hydrogen-bonded polymer complex films with the thickness ranging from 50 nm to 2400 nm were prepared by layer-by-layer (LbL) assembly of poly(2-ethyl-2-oxazoline) (PEOX) and poly(acrylic acid) (PAA). The dewetting behavior of PEOX/PAA films under hydrothermal condition was investigated. It was found that the dewetting occurred at solid-liquid interface, and the typical morphologies such as holes, irregular cellular structure, and droplets were observed. Atomic force microscopy (AFM) revealed the initial rupture of the film. Microscopic Raman and infrared (IR) imaging demonstrated that the PEOX and PAA chains remained association during the dewetting process.
Improved Mechanical Properties of Poly(butylene succinate) Membrane by Co-electrospinning with Gelatin
Lu Chen, Hui-Hui Cheng, Jiang Xiong, Ya-Ting Zhu, Hong-Peng Zhang, Xi Xiong, Yu-Man Liu, Jian Yu, Zhao-Xia Guo
In press , doi: 10.1007/s10118-018-2112-0
[Abstract](177) [FullText HTML](97) [PDF 1216KB](12)
Abstract:
Gelatin, a natural proteinous polymer, was used to co-electrospin with poly(butylene succinate) (PBS) in order to improve the mechanical properties of PBS membrane and facilitate its applications in biomedical field. The PBS/gelatin blend membranes have narrower distribution of fiber diameter and smoother surface than neat PBS membrane. The contact angles, water absorption rates and water uptakes of the PBS/gelatin blend membranes were measured, showing increased hydrophilicity. The interaction between PBS and gelatin was investigated by attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR) and differential scanning calorimetry (DSC). The mechanical properties of PBS/gelatin blend membranes in both dry and wet states were evaluated by uniaxial tensile tests. In the dry state, the PBS/gelatin blend membrane containing 10% gelatin has a 3-times increase in tensile strength without any adverse effect on ductility because of the existence of interaction between the two blend components, little change in crystallinity of PBS, and possible interaction between any adjacent fibers; the tensile strength and elongation at break are even better in the wet state attributed to some gelatin on fiber surfaces, which act as a binder in the presence of water. The potential applications of PBS/gelatin blend membranes were demonstrated by successful immobilization of thrombin, a clinically-used hemostatic drug. The thrombin-loaded membrane could be used for rapid hemostasis.
Structures and Surface States of Polymer Brushes in Good Solvents: Effects of Surface Interactions
Yi-Xin Liu, Hong-Dong Zhang
In press , doi: 10.1007/s10118-018-2100-4
[Abstract](149) [FullText HTML](76) [PDF 1435KB](4)
Abstract:
The influence of the surface interaction on the mesoscopic structure of grafted polymers in good solvents has been examined. At high surface coverage, tethered polymers are in the brush state and the parabolic segment density profile is confirmed by self-consistent field theory (SCFT) calculations. It is found that this is a universal behavior for a whole range of surface interactions from complete repulsion to strong attraction. More interestingly, finite surface repulsion may lead to the maximum in the proximal layer of its segment density profile, which is significantly different from both the depletion layer of pure repulsion and the adsorbing layer of attraction. In addition to the brush state on both repulsive and attractive surfaces, three additional surface states were identified by analyzing the scaling behavior of the layer thickness of polymer brushes: the mushroom state on repulsive substrates, the dilute and the semidilute surface states on attractive substrates.
Synthesis and Characterization of Butyl Acrylate-based Graft Polymers with Thermo-responsive Branching Sites via the Diels-Alder Reaction of Furan/Maleimide
Lin Ye, Shao-Feng Zhang, Yi-Chao Lin, Jia-Kang Min, Li Ma, Tao Tang
In press , doi: 10.1007/s10118-018-2107-x
[Abstract](152) [FullText HTML](114) [PDF 1115KB](9)
Abstract:
Thermo-responsive butyl acrylate/furfuryl methacrylate copolymer-based (PBF backbone) graft (co)polymers with dynamic covalent linkages between their backbones and side chains via the Diels-Alder reaction of furan/maleimide were synthesized. Atom transfer radical polymerization (ATRP) was used to synthesize graft copolymers with thermo-responsive transformation from graft copolymers to linear polymers with bimodal or wide MWD. The NMR measurements indicated that the Diels-Alder reaction and retro-Diels-Alder reaction occurred, depending on the change of the temperature, meaning that the side chains could be cleaved and reformed according to the variation of the temperature. GPC measurements demonstrated that the molecular weights of the polymers were thermo-responsive. Furthermore, three graft copolymers with various branching chains (PBF-g-PBA, PBF-g-P(BMA-co-MA) and PBF-g-PBMA) were compared to study the influence of compatibility between the backbone and the branching chain on the efficiency of Diels-Alder reaction after the cleavage of the DA linkage. The results showed that the ability of the side chains to come back to the main chain was strongly affected by the compatibility between the backbone and the side chains and the flexibility of the polymer chains.
Humidity-responsive Bilayer Actuators Comprised of Porous and Nonporous Poly(acrylic acid)/Poly(allylamine hydrochloride) Films
Miao Zheng, Tang-Jie Long, Xiao-Ling Chen, Jun-Qi Sun
In press , doi: 10.1007/s10118-0182162-3
[Abstract](94) [FullText HTML](45) [PDF 630KB](11)
Abstract:
Bilayer humidity-responsive actuators are generally composed of actuating and supporting layers of different materials with largely different wettability. Such kinds of bilayer actuators suffer from low adhesive force between the two layers during usage. This study demonstrates the preparation of humidity-responsive bilayer actuators that have the same materials in the actuating and supporting layers to avoid the adhesive issue. The bilayer actuators comprise a porous poly(acrylic acid) (PAA)/poly(allylamine hydrochloride) (PAH) layer and a nonporous PAA/PAH layer that are fabricated by exponentially layer-by-layer assembly method. At a high/low relative humidity (RH), the nonporous PAA/PAH layer can efficiently expand/shrink by absorbing/desorbing water while the volume expansion/shrinkage of the porous PAA/PAH layer in an environment with changed humidity is significantly suppressed by the micrometer-sized pores. The largely different expansion/shrinkage of the nonporous and porous PAA/PAH layers when subjected to humidity changes enables rapid and reversible rolling/unrolling motions of the bilayer actuator. The bilayer actuator shows a faster rolling speed and a larger bending curvature when subjected to a larger humidity increase.
Antistatic PVC-graphene Composite through Plasticizer-mediated Exfoliation of Graphite
Zi-Bo Wei, Yang Zhao, Chao Wang, Shigenori Kuga, Yong Huang, Min Wu
In press , doi: 10.1007/s10118-018-2160-5
[Abstract](46) [FullText HTML](34) [PDF 1180KB](9)
Abstract:
Multilayer graphene was prepared by mechanical exfoliation of natural graphite with dioctyl phthalate (DOP) as milling medium without solvent. The obtained mixture could be directly mixed with poly(vinyl chloride) (PVC) for melt-forming, DOP acting as plasticizer and graphene acting as conductive filler for antistatic performance. The composite showed surface resistance of 2.5 × 106 ohm/square at 1wt% carbon, significantly lower than approx. 7wt% of raw graphite required for achieving the same level. This level is low enough for practical antistatic criterion of 3 × 108 ohm/square. The effect of filler addition on mechanical performance was minimal, or even beneficial for the milled carbon in contrast to the case of raw graphite.
Comb-like Poly (N-(2-hydroxypropyl) methacrylamide) Doxorubicin Conjugates: The Influence of Polymer Architecture and Composition on the Biological Properties
Hao Tang, Jin Tang, Yi Shen, Wen-Xuan Guo, Min Zhou, Rui-Hua Wang, Ni Jiang, Zhi-Hua Gan, Qing-Song Yu
In press , doi: 10.1007/s10118-018-2159-y
[Abstract](36) [FullText HTML](40) [PDF 1305KB](1)
Abstract:
The synthesis and structure-property correlation of poly (N-(2-hydroxypropyl) methacrylamide) (PHPMA) conjugates with various architectures including random, block, branched or star-like structures and compositions have been thoroughly explored. However, related synthesis and structure-property data are still lacking for comb-like PHPMA. In this work, we report the synthesis of comb-like PHPMA copolymer-doxorubicin (DOX) conjugates with different backbone/side chain lengths and location of drug moieties. Well-defined comb-like PHPMA-DOX conjugates are obtained via the combination of controlled radical polymerization and fractional precipitation techniques. The influences of structural factors on the biological properties such as cellular uptake, blood circulation and tumor accumulation have been investigated. Long blood circulation and efficient tumor accumulation can be achieved by proper control of the comb number, length and location of drug moieties. These facile comb-like structures possess great potentials in future theranostics for brachytherapy or surgical navigation.
Thermodynamics of Aromatic Cyclic Ester Polymerization in Bulk
Chong He, Xiang Zhu, Xiao-Hong Li, Xiao-Ming Yang, Ying-Feng Tu
In press , doi: 10.1007/s10118-018-2161-4
[Abstract](111) [FullText HTML](32) [PDF 464KB](1)
Abstract:
We present here the thermodynamic investigation of in situ cascade polycondensation-coupling ring-opening polymerization (PROP) for three cyclic aromatic ester monomers, i.e., cyclic oligo(2-methyl-1,3-propylene terephthalate)s (COMPTs), cyclic oligo(neopentylene terephthalate)s (CONTs) and cyclic oligo(2-methyl-2-propyl-1,3-propylene terephthalate)s (COMPPTs). The equibrium monomer to polymer weight ratio in bulk at different polymerization temperatures for each monomer was estimated by the size exclusion chromatography (SEC), and the thermodynamic parameters are estimated by Dainton equation. Quite different to the thermodynamics of aliphatic lactones polymerization, which is an exothermic process with entropy reduction, our results show the polymerization thermodynamics for three cyclic aromatic ester monomers is a weak exothermic process with slightly entropy increment, i.e., a both enthalpy and entropy driving process. Among them, CONTs shows the largest value of enthalpy change, due to its symetric dimethyl substitution on β-position of propandiol segments.
Co-delivery of Andrographolide and Notch1-targeted siRNA to Macrophages with Polymer-based Nanocarrier for Enhanced Anti-inflammation
Teng Wu, Min Tan, Heng-Ye Gong, Yong Wang, Xin-Tao Shuai
In press , doi: 10.1007/s10118-018-2158-z
[Abstract](104) [FullText HTML](96) [PDF 821KB](6)
Abstract:
Chronic inflammatory responses induced by macrophages play a pivotal role in the progression of atherosclerosis. In the present study, a multifunctional nanocarrier based on PEG-PAsp(DETA)-Lys-CA2 polymer was synthesized for co-delivery of andrographolide and siRNA targeting Notch1 gene to alleviate the inflammatory response in macrophages. The nanocarrier exerted low cytotoxicity as well as high performance in drug/siRNA co-delivery. In vitro studies demonstrated the co-delivery of andrographolide and Notch1 siRNA not only significantly inhibited lipopolysaccharide (LPS)-activated interleukin-6 (IL-6) and monocytes chemotactic protein 1 (MCP-1) expression as well as blocked nuclear factor-κB (NF-κB) signal activation, but also interfered the Notch-1 gene expression and increased anti-inflammatory cytokines such as Interleukin-10 (IL-10) and Arginase-1 expression obviously in macrophages. These results suggested that the combination therapy based on Notch1 siRNA and andrographolide co-delivered nanocarrier, i.e. suppressing the expression of pro-inflammatory cytokines simultaneously increasing anti-inflammatory factors expression, be a feasible strategy for atherosclerosis treatment.
pH-responsive Micelles from a Blend of PEG-b-PLA and PLA-b-PDPA Block Copolymers: Core Protection Against Enzymatic Degradation
Yan-Ling Xu, Ao-Ting Qu, Ru-Jiang Ma, Ang Li, Zhen-Kun Zhang, Zhi-Qiang Shang, Yao-Fang Zhang, Lu-Xia Bu, Ying-Li An
In press , doi: 10.1007/s10118-018-2149-0
[Abstract](95) [FullText HTML](40) [PDF 687KB](0)
Abstract:
pH-responsive micelles with a biodegradable PLA core and a mixed PEG/PDPA shell were prepared by self-assembly of poly(ethylene glycol)-b-poly(lactic acid) (PEG-b-PLA) and poly(2-(diisopropylamino) ethyl methacrylate)-b-poly(lactic acid) (PDPA-b-PLA). The micellization status with different pH and the enzyme degradation behavior were characterized by using 1H-NMR spectra, dynamic light scattering measurement and zeta potential test. The pH turning point of PDPA block was determined to be in the range of 5.5−7.0. While the pH was above 7.0, the PDPA block collapsed onto the PLA core and could protect the PLA core from the invasion of enzyme, as a result, the micelle exhibited a resistance to the enzymatic degradation.
Mesoscopic Simulation Assistant Design of Immiscible Polyimide/BN Blend Films with Enhanced Thermal Conductivity
Guo-Dong Zhang, Lin Fan, Lan Bai, Min-Hui He, Lei Zhai, Song Mo
In press , doi: 10.1007/s10118-018-2155-2
[Abstract](64) [FullText HTML](38) [PDF 1529KB](4)
Abstract:
The mesoscopic simulation technique was applied to describe the phase separation behavior of polyimide blends and used for design the immiscible polyimide/BN blend films with enhanced thermal conductivity. The simulation equilibrium morphologies of different poly(amic acid) (PAA) blend systems were investigated and compared with optical images of corresponding polyimide blend films obtained by experiment. The immiscible polyimide blend films containing nano-/micro-sized BN with vertical double percolation structure were prepared. The result indicated that the thermal conductivity of polyimide blend film with 25 wt% of nano-sized BN reached 1.16 W/(m·K), which was 236% increment as comparing with the homogenous film containing the same BN ratio. The significant enhancement in thermal conductivity was attribute to the good phase separation of polyimide matrix, which lead the inorganic fillers selectively localized in one continuous phase with high packing density, consequently, forming the effective thermal conductive pathway.
The Crystallization, Melting Behaviors and Thermal Stability of Cross-linked Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) by Octavinyloctasilasesquioxane
Heng-Xue Xiang, Elham Zabihi, Xu-Zhen Zhang, Mei-Fang Zhu
In press , doi: 10.1007/s10118-018-0000-0
[Abstract](61) [FullText HTML](33) [PDF 984KB](1)
Abstract:
A series of cross-linked poly(3-hydroxybutyrate-co-3-hydroxyvalerate)/octavinyloctasilasesquioxane (PHBV/OVS) composites were obtained by a simple melt reactive processing technique. Dicumyl peroxide (DCP) and OVS were employed as free radical initiator and cross-linking agent, respectively. The chemical structure of these produced composites were identified by 1H/13C/29Si nuclear magnetic resonance spectroscopy (1H/13C/29Si NMR) and Fourier transform infrared spectroscopy (FTIR). The melting behavior, non-isothermal crystallization, spherulite morphology and thermal stability property of PHBV/OVS composites were also investigated. The nucleation behaviors and crystallization rate of PHBV/OVS were significantly enhanced with the formation of cross-linked networks with different of side-chains and cross-linking points. The red shift of crystalline peak temperature with increase of small amount of OVS content evidenced the higher crystalline ability compared with the neat PHBV. However there was threshold content beyond it the crystallization rate weakened again. Additionally, the degree of cross-linked structure of PHBV/OVS composites could be adjusted by changing the usage amount of OVS.
Controlled Radical Polymerization of Styrene Mediated by Xanthene-9-thione and Its Derivatives
Hao-Yu Yu, Jiao Wang, Jian-Wei Shao, Dong Chen, Shi-Chao Wang, Li Wang, Wan-Tai Yang
In press , doi: 10.1007/s10118-018-2153-4
[Abstract](83) [FullText HTML](50) [PDF 452KB](9)
Abstract:
In our present work, a novel controlled radical polymerization system is developed based on xanthene-9-thione (XT). It was found that the radical polymerization of styrene (St) became controlled in the presence of a small amount of XT. At the early stage of the polymerization, the polymerization rate was relatively low and the as-formed polystyrene (PS) had low number-average molecular weight (Mn) and narrow polydispersity (Ð). After XT was consumed, the polymerization rate increased dramatically and the Mn of PS increased gradually with polymerization proceeding. When the polymerization of St was carried out with a proper molar ratio of initiator to XT and at an appropriate temperature, shortened slow polymerization stage and good control over Mn could be achieved. To further improve the regulating ability of XT, a series of substituent groups (―CF3, ―CH(CH3)2, ―N(CH3)2) were introduced onto the xanthene ring of XT, and the effects of these derivatives on the polymerization of St were investigated in detail. UV-Vis spectroscopy was carried out to monitor the concentration of XT during the polymerization and the chemical structure of the as-formed PS was fully characterized by 1H-NMR and ESI-MS analysis. A possible mechanism involving the formation and evolution of the cross-termination products was proposed to interpret the observed polymerization behavior.
A Comparison Study of Physicochemical Properties and Stabilities of H-Shaped Molecule and the Corresponding Polymer
Quan-You Feng, Bin Li, Zong-Yan Zuo, Song-Lin Xie, Meng-Na Yu, Bin Liu, Ying Wei, Ling-Hai Xie, Rui-Dong Xia, Wei Huang
In press , doi: 10.1007/s10118-018-2152-5
[Abstract](62) [FullText HTML](35) [PDF 709KB](1)
Abstract:
Rare attention has been paid to the comparison between a monomer and its corresponding polymer in terms of the optoelectronic characteristics. In this article, a model H-shaped molecule and its corresponding polymer, both of which exhibited similar properties including blue emission and solution processing, were designed and synthesized. Optoelectronic properties and various kinds of stability features, including the thermostabilities, spectral stabilities and amplified spontaneous emission characteristic of the monomer and polymer were investigated. In general, the corresponding polymer PH exhibited similar optoelectronic properties but deteriorated stabilities compared with its H-shaped monomer H-1 probably owing to the similar chemical structure but the wider molecular weight distribution and metal catalyst residue. Imporantly, monomer H-1 displayed a comparable ASE threshold value with its polymer PH, suggesting that H-shaped fluorene-based small molecules may be more promising optical gain media in solid state amplifers and lasers.
Slow Down Dewetting in Polymer Films by Isocyanate-treated Graphite Oxide
Yong Zhou, Pei Bai, Miao Huo, Yu-Jie Chen, Hua Li, Hong-Mei Kang, He-Zhou Liu, Yun-Long Guo
Corrected proof , doi: 10.1007/s10118-018-2147-2
[Abstract](71) [FullText HTML](55) [PDF 1568KB](11)
Abstract:
Isocyanate-treated graphite oxides (iGOs) were well-dispersed into the polystyrene (PS) thin films and formed a novel network structure. With control in fabrication, an iGOs-web layer was horizontally embedded near the surface of the films and thus formed a composite slightly doped by iGOs. This work demonstrated that the iGOs network can remarkably depress the dewetting process in the polymer matrix of the composite, while dewetting often leads to rupture of polymer films and is considered as a major practical limit in using polymeric materials above their glass transition temperatures (Tg). Via annealing the 50-120 nm thick composite and associated neat PS films at temperatures ranging from 35 °C to 70 °C above Tg, surface morphology evolution of the films was monitored by an atomic force microscopy (AFM). The iGOs-doped PS exhibited excellent thermal stability, i.e., the number of dewetting holes was greatly reduced and the long-term hole growth was fairly restricted. In contrast, the neat PS film showed serious surface fluctuation and a final rupture induced by ordinary dewetting. The method developed in this work may pave a road to reinforce thin polymer films and enhance their thermal stability, in order to meet requirements by technological advances.
Preparation of Aryloxy-aluminoxanes and Their Use as Activators in the Bis(imino)pyridyl Iron-catalyzed Oligomerization of Ethylene
Wei Zhang, Bin-Bo Jiang#, Jian Ye, Zu-Wei Liao, Zheng-Liang Huang, Jing-Dai Wang, Yong-Rong Yang
Corrected proof , doi: 10.1007/s10118-018-2146-3
[Abstract](252) [FullText HTML](57) [PDF 870KB](33)
Abstract:
In this study, a series of aryloxy-aluminoxanes originated directly from the hydrolysis of reaction products of AlMe3 and phenols were synthesized, which can serve as effective polymer-retarding activators for the iron-catalyzed ethylene oligomerization. The molar ratios of [PhOH]/[AlMe3] and [H2O]/[Al] during the preparation were explored and their impacts on the oligomerization activity and product distribution were discussed. To obtain the effective activators with good polymer-retarding effect and relatively high activity, the optimized conditions were proposed to be [PhOH]/[AlMe3] = 0.5 and [H2O]/[Al] = 0.7. Various aluminoxanes with different [―OH] sources confirmed the importance of using phenols in preparing the effective polymer-retarding activators. By utilizing these aryloxy-aluminoxanes, the mass fraction of polymers in the total products could be reduced to lower than 1.0 wt%, which is much lower than that of the MAO-activated systems (> 30 wt%). This is a potential benefit for the industrial application of the iron-catalyzed oligomerization process.
Preparation and Characteristics of Poly(butylene adipate-co-terephthalate)/Polylactide Blend Films via Synergistic Efficiency of Plasticization and Compatibilization
Worasak Phetwarotai, Neeranuch Phusunti, and Duangdao Aht-Ong
Accepted Manuscript , doi: 10.1007/s10118-019-2174-7
[Abstract](38) [PDF 0KB](0)
Abstract:
Polylactide (PLA) films blended with poly(butylene adipate-co-terephthalate) (PBAT) were hot melted using a twin screw extruder with the addition of triethyl citrate (TEC) as a plasticizer and toluene diisocyanate (TDI) as a compatibilizer. We investigated the synergistic effects of the two additives on the mechanical, thermal, and morphological properties of the PLA/PBAT blend films. We also studied the influence of TEC content on the plasticized PLA films and the presence of TDI on the PLA/PBAT blend films, and compared the results to those of neat PLA. The results showed a pronounced increase of the elongation at break of the plasticized PLA films with increasing TEC levels, but a slight reduction in thermal stability. Also, the addition of TEC and TDI to the blend system not only synergistically enhanced the tensile properties and tensile-impact strength of the PLA/PBAT blends, but also affected its crystallinity and cold crystallization rate, a result of the improvement of the interfacial interaction between PLA and PBAT, including the enhancement of their chain mobility. The synergy of the plasticization and compatibilization processes led to the improvement of the tensile properties, tensile-impact strength, and compatibility of the blends, accelerating cold crystallization but not affecting crystallization.

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Chinese Journal of Polymer Science 2018 (Volume 36) Number7 Contents
2018, 36(7): 0-0  
[Abstract](27)
Abstract:
RAPID COMMUNICATION
Enantiomer-selective Living Polymerization of rac-Phenyl Isocyanide Using Chiral Palladium Catalyst
Jian Huang, Ling Shen, Hui Zou, Na Liu
2018, 36(7): 799-804   doi: 10.1007/s10118-018-2136-5
[Abstract](210)
Abstract:
We report the polymerization of phenyl isocyanides with the chiral palladium(II) initiating system. The resulting polymers with optically active properties were obtained by polymerization of the racemic isocyanide monomer (rac-1), and enantiomerically unbalanced polymerization of the monomer was found, providing substantial evidence for the enantiomer-selective polymerization of rac-1 mediated through chiral catalyst. A comparison between the enantiomerically pure monomers, 4-isocyanobenzoyl-L-alanine decyl ester (1s) and 4-isocyanobenzoyl-D-alanine decyl ester (1r), revealed a drastic discrepancy in the reactivity ratio of their homopolymerizations. It turned out that the monomer reactivity ratio of 1s was higher than that of 1r with chiral ligands. The results clearly demonstrated the inclination for incorporation of the 1s enantiomer during the polymerization process and thus resulted in the enantiomer-selective polymerization in this system. The effects of the catalyst chirality on the optically active properties of polymerization were investigated, and it was concluded that the formation of higher-ordered conformation with a handed helicity might be attributed to the chiral induction of chiral palladium(II) catalyst. Moreover, the polymers obtained through the enantiomer-selective polymerization of the enantiomerically pure monomer were with a significant improvement of the optical activity if the chirality of the monomer and the catalyst matched with each other.
Thioxanthene-9-thione Mediated MMA Polymerization
Xu Yan, Guan Wang, Li-Hua Zhang, Li Wang, Xiao-Fei Liu, Wan-Tai Yang
2018, 36(7): 805-810   doi: 10.1007/s10118-018-2140-9
[Abstract](154)
Abstract:
In the " cycloketyl radical mediated living polymerization” (CMP) process, a cycloketyl compound, [9,9′]bixanthenyl-9,9′ diol (BIXAN) was ultilized as initiator and mediator. The cycloketyl (CK) radical was used as the dormant radical to achieve the increase of molecular weight. Herein, a series of cycloketyl thioketones were synthesised by Lawesson’s reagent by one step reaction with high yeild, and we found that, when a special cycloketyl thioketone compound, thioxanthene-9-thione (TXT), was added to a routine radical polymerization system, TXT could capture chain radical, and simultaneously formed an radical analogous to CK radical in structure, which could trigger the growth of polymer chains. This simple system was efficient to initiate the polymerization of methyl methacrylate (MMA) and in all cases the molecular weights increased with the increase of conversions. By the end-group analysis with 1H-NMR and MALDI-TOF MS, it was confirmed that the P-STXT radical was used to control the polymerization. The re-initiating reactions were achieved when PMMA was used as the macro-initiator.
FEATURE ARTICLE
Self-assembly and Properties of Block Copolymers Containing Mesogen-Jacketed Liquid Crystalline Polymers as Rod Blocks
Xiao-Lin Lyu, Hong-Bing Pan, Zhi-Hao Shen, Xing-He Fan
2018, 36(7): 811-821   doi: 10.1007/s10118-018-2115-x
[Abstract](136)
Abstract:
Mesogen-jacketed liquid crystalline polymer (MJLCP) has attracted great attention because of its rigid conformation, facile synthesis, and structural controllability. In this feature article, the self-assembly of MJLCP-based block copolymers (BCPs) is briefly reviewed, especially the nanostructures of rod-coil diblock copolymers (diBCPs), rod-rod diBCPs, and triblock copolymers. In addition, the properties of the self-assembled BCPs are also summarized, including their applications as liquid crystalline thermoplastic elastomers and solid polymer electrolytes. The article also discusses the major challenges and future directions in the study of MJLCP-based BCPs.
ARTICLE
Magnetic and Heat Resistant Poly(imide-ether) Nanocomposites Derived from Methyl Rich 9H-xanthene: Synthesis and Characterization
Khalil Faghihi, Hassan Moghanian, Fatemeh Mozafari, Meisam Shabanian
2018, 36(7): 822-834   doi: 10.1007/s10118-018-2094-y
[Abstract](174)
Abstract:
In this study a new series of magnetic and heat resistant nanocomposites were prepared based on a highly soluble poly(imide-ether) (PIE) reinforced with two different types of magnetic nanoparticles via a solution intercalation technique. New PIE with good solubility and desired molar mass containing bulky xanthene rings and amide groups in the side chains was synthesized via thermal cyclization of the poly(amic acid) precursor, obtained from the reaction of a new diamine derived from 9H-xanthene and 4,4′-oxydiphthalic dianhydride (ODPA). Improved solubility was attributed to the presence of xanthene group and flexible ether linkage in the polyimide backbones that reduce the chain-chain interaction and enhance solubility by penetrating solvent molecules into the polyimide chains. Fe3O4 nanoparticles (MNPs) which synthesized from chemical co-precipitation route were coated with silica (SiO2), sequentially with (3-aminopropyl)triethoxysilane and poly-melamine-terephthaldehyde (MNPs-PMT), and then separately dispersed in the poly(amic acid) solutions and thermally imidized to form PIE/Fe3O4 and PIE/MNPs-PMT nanocomposites. The nanostructures and properties of the resultant materials were investigated using FTIR spectroscopy, X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM), vibrating sample magnetometer (VSM), thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC). The properties of the nanocomposites were strongly related to the dispersion and interaction between the nanoparticles and PIE matrix. The thermogravimetric analysis (TGA) results showed that the addition of MNPs-PMT nanoparticles resulted in a substantial increase in the thermal stability of the corresponding PIEN. The temperature at 10% weight loss (T10) was increased from 416 °C to 428 °C for PIEN containing 3 wt% MNPs-PMT as compared to neat PIE, as well the char yield enhanced. Furthermore, the MNPs-PMT nanoparticles had better dispersion in the polymer matrix due to the strong intermolecular hydrogen bond interactions between the NH and C=N groups of surface-modified nanoparticles and the PIE matrix than the uncoated Fe3O4 nanoparticles, and exhibited a better intercalated morphology and improved thermal properties. Also, the PIEN nanocomposites under applied magnetic field exhibited the hysteretic loops of the superparamagnetic nature.
New Polymer Syntheses Part 60: A Facile Synthetic Route to Polyamides Based on Thieno[2,3-b]thiophene and Their Corrosion Inhibition Behavior
Kamal I. Aly, Amr H. Moustafa, Essam K. Ahmed, Hany M. Abd El-lateef, Mohamed Gamal Mohamed, Sahar M. Mohamed
2018, 36(7): 835-847   doi: 10.1007/s10118-018-2101-3
[Abstract](174)
Abstract:
Polyamides containing thieno[2,3-b]thiophene moiety were prepared via a simple polycondensation reaction of the diaminothieno[2,3-b]thiophene monomer 1a with different kinds of diacid chlorides (including oxalyl, adipoyl, sebacoyl, isophthaloyl, terephthaloyl, 4,4′-azodibenzoyl, 3,3′-azodibenzoyl, p-phenylene diacryloyl) in the presence of LiCl and NMP as a solvent through low-temperature solution polycondensation. The chemical structures of model compound and synthesized polyamides were confirmed by FTIR, nuclear magnetic resonance spectroscopy (including 1H-NMR and 13C-NMR) and elemental analysis. In addition, the thermal stability, crystallinity structure and surface morphology of synthesized polyamides were characterized via thermogravametric analysis (TGA), wide-angle X-ray diffraction analysis (WAXD) and scanning electron microscopy (SEM). Also, the corrosion inhibition behavior of selected examples of polyamides was investigated; the inhibitive effect of the investigated polymers for carbon steel in 1.0 mol·L−1 HCl was studied using potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS) methods. PDP results displayed that the polyamides containing thieno[2,3-b]thiophene moiety can be as mixed-type inhibitors. The inhibition efficiency (P, %) was found to be in the range from 67.13% to 96.01%. There is an increase in P by the synthesized polymers in comparison to the starting monomer. The adsorption of these polymers was found to obey Langmuir adsorption isotherm.
Correlation of Morphology Evolution with Superior Mechanical Properties in PA6/PS/PP/SEBS Blends Compatibilized by Multi-phase Compatibilizers
Huanmin Li, Xianwei Sui, Xu-Ming Xie
2018, 36(7): 848-858   doi: 10.1007/s10118-018-2102-2
[Abstract](193)
Abstract:
In this study, the maleic anhydride (MAH) and styrene (St) dual monomers grafted polypropylene (PP) and poly[styrene-b-(ethylene-co-butylene)-b-styrene] (SEBS), i.e. PP-g-(MAH-co-St) and SEBS-g-(MAH-co-St) are prepared as multi-phase compatibilizers and used to compatibilize the PA6/PS/PP/SEBS (70/10/10/10) model quaternary blends. Both PS and SEBS are encapsulated by the hard shell of PP-g-(MAH-co-St) in the dispersed domains (about 2 μm) of the PA6/PS/PP-g-(MAH-co-St)/SEBS (70/10/10/10) quaternary blend. In contrast, inside the dispersed domains (about 1 μm) of the PA6/PS/PP/SEBS-g-(MAH-co-St) (70/10/10/10) quaternary blend, the soft SEBS-g-(MAH-co-St) encapsulates both the hard PS and PP phases and separates them. With increasing the content of the compatibilizers equally, the morphology of the PA6/PS/(PP+PP-g-(MAH-co-St))/(SEBS+SEBS-g-(MAH-co-St)) (70/10/10/10) quaternary blends evolves from the soft (SEBS+SEBS-g-(MAH-co-St)) encapsulating PS and partially encapsulating PP (about 1 μm), then to PS exclusively encapsulated by the soft SEBS-g-(MAH-co-St) and then separated by PP-g-(MAH-co-St) inside the smaller domains (about 0.6 μm). This morphology evolution has been well predicted by spreading coefficients and explained by the reaction between the matrix PA6 and the compatibilizers. The quaternary blends compatibilized by more compatibilizers exhibit stronger hierarchical interfacial adhesions and smaller dispersed domain, which results in the further improved mechanical properties. Compared to the uncompatibilized blend, the blend with both 10 wt% PP-g-(MAH-co-St) and 10 wt% SEBS-g-(MAH-co-St) has the best mechanical properties with the stress at break, strain at break and impact failure energy improved significantly by 97%, 71% and 261%, respectively. There is a strong correlation between the structure and property in the blends.
Fractionated and Confined Crystallization of Polybutene-1 in Immiscible Polypropylene/Polybutene-1 Blends
Yao Xu, Chen-Guang Liu, Hua-Rong Nie, Ai-Hua He
2018, 36(7): 859-865   doi: 10.1007/s10118-018-2103-1
[Abstract](192)
Abstract:
In this work, the crystallization of immiscible polypropylene (PP)/polybutene-1 (PB) blends, in particular the effect of crystal morphology of PP (HTC, high Tm component) on the subsequent crystallization behavior of PB (LTC, low Tm component) was studied. Herein, we firstly indicated that PP/PB blends were not completely compatible but characterized as the LCST-like phase diagram above the melting temperature of PP. Crystallization of PP at different crystallization temperatures brought about different PP crystal morphologies and PB was segregated and confined at different locations. Much larger-sized domain of PB component appeared in PP spherulites resulting from the effects of non-negligible phase separation and the slower PP crystallization rate as PP crystallized at high temperature. As temperature continued to fall below Tm of PB, the fractionated and confined crystallization of PB occurred in the framework of PP spherulites, reflected by the decreased crystallization temperature (Tc) of PB and the formation of form I′ beside form II. Notably, if PP previously crystallized at high Tc, fractionated crystallization of PB became predominant and confined crystallization of PB became weak due to the much wider droplet-size distribution of PB domains.
Prominently Promoting the Formation of Poly(butylene adipate) α-Form Crystals by Coalescing from Inclusion Complex
Hai-Mu Ye, Xiao-Tong Chen, Ping Liu, Na Yan
2018, 36(7): 866-870   doi: 10.1007/s10118-018-2095-x
[Abstract](219)
Abstract:
We successfully use a co-precipitation method to prepare inclusion complex between poly(butylene adipate) (PBA) chains (guest component) and urea molecules (host component). The PBA/urea inclusion complex is confirmed to adopt a hexagonal crystal modification with lattice parameters of a = 8.14 Å and c = 10.92 Å, and the interaction between PBA chains and urea is van der Waals force. The singly isolated PBA chains are suggested to take some gauche conformation, which is different from the all-trans conformation in β-form PBA. Furthermore, we employ the isolated PBA chains which are uniformly pre-established in a specific conformation in urea channels to regulate the crystal form of PBA for the first time. After removing the host urea molecules, the coalesced PBA chains are found to solely crystallize into α-form crystals at different coalescing temperatures. By comparing the FTIR spectra, it is found that PBA chains in inclusion complex plausibly contain some similar conformers as those in α-form crystal, which is suggested to be the intrinsic reason for the sole formation of α-form crystals. This research proves that inclusion complex can be used as a very effective method to regulate polymorphism of semi-crystalline polymers.
Crystallization, Mechanical and Flame-retardant Properties of Poly(lactic acid) Composites with DOPO and DOPO-POSS
Lin Jia, Wen-Chao Zhang, Bin Tong, Rong-Jie Yang
2018, 36(7): 871-879   doi: 10.1007/s10118-018-2098-7
[Abstract](213)
Abstract:
Poly(lactic acid) (PLA) composites with 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO) and DOPO-containing polyhedral oligomeric silsesquioxane (DOPO-POSS) were prepared via melting extrusion and injection molding. The crystallization, mechanical, and flame-retardant properties of PLA/DOPO and PLA/DOPO-POSS were investigated by differential scanning calorimetry (DSC), X-ray diffraction (XRD), tensile testing, thermogravimetric analysis (TGA), limiting oxygen index (LOI), and cone calorimeter test. The DSC results showed that the DOPO added could act as a plasticizer as reflected by lower glass transition temperature and inhibited crystallization of part of the PLA; the DOPO-POSS acted like a filler in the PLA matrix and slightly improved the crystallinity of the PLA matrix. The XRD and DSC analyses indicated that the PLA composites by cold molding injection were amorphous, and the PLA composites following a heat treatment in an oven at 120 °C for 30 min achieved crystallinity. All the PLA and its composites after heat treatment had improved mechanical properties. The thermogravimetric analysis (TGA) tests showed that the PLA, DOPO and DOPO-POSS decomposed separately in the PLA/DOPO and PLA/DOPO-POSS, respectively. The cone calorimeter tests offered clear evidence that addition of the DOPO-POSS resulted in an evident reduction of 25% for the peak of heat release rate (p-HRR). It was also confirmed that the crystalline flame-retardant PLA composites after heat treatment had better flame retardant properties than the amorphous PLA composites prepared by the cold molding.
Vertically Oriented Microporous Membranes Prepared by Bidirectional Freezing
Sen-He Chen, Bai-Heng Wu, Jin-Cheng Fu, Guo-Jun Wang, Ling-Shu Wan, Zhi-Kang Xu
2018, 36(7): 880-887   doi: 10.1007/s10118-018-2113-z
[Abstract](143)
Abstract:
Polystyrene membranes with precisely controlled and vertically oriented pores are fabricated by a bidirectional freezing process. In this process, the influence of polymer in growth of diphenyl sulfone (DPS) crystals has been demonstrated by XRD and simulated by DFT based on the interaction between DPS crystal faces and polystyrene (PS). The influence of temperature gradient on membrane structures is also elucidated. Compared to the original membrane and modified traditional membranes, modified PS membranes with vertically oriented pores show large and stable fluxes in the processes of multiple oil and water separation.
Self-assembly Behavior of Symmetrical Linear ABCA Tetrablock Copolymer: A Self-consistent Field Theory Study
Dan Liu, Ying-Ying Wang, Ying-Chun Sun, Yuan-Yuan Han, Jie Cui, Wei Jiang
2018, 36(7): 888-896   doi: 10.1007/s10118-018-2106-y
[Abstract](137)
Abstract:
ABCA tetrablock copolymers offer new opportunities for design of materials with novel structures. Using real-space self-consistent field theory and simulation, we systematically examined the self-assembly behavior of linear ABCA tetrablock copolymers in a 2D space. The simulation was carried out under conditions of symmetrical compositions and interactions. We focus on the influence of chain length ratio of block A and interactions between block A and other blocks B and C on the self-assembly behavior of the copolymer system. The simulation results show that most of the structures self-assembled by the ABCA tetrablock copolymers are centrosymmetric, such as diblock-like lamella phase, two kinds of lamellae with beads at interface, two kinds of hierarchical lamella phase, hexagonal honeycomb-like phase, lamella phase with mixed BC and hexagonal spheres with mixed BC. Furthermore, we find that a novel noncentrosymmetric Janus spheres can be obtained when the interaction between blocks B and C is strong, whereas a noncentrosymmetric lamella phase was obtained at weak interaction between blocks B and C. Phase diagrams for the ABCA tetrablock copolymers with different interaction strength between blocks B and C are constructed by comparing free energies of candidate ordered structures. In addition, studies on the metastable behavior of the system reveal that enthalpy plays an important role in the metastable behavior of the ABCA tetrablock copolymer system. Our work can provide useful guide for structure control of such kind of tetrablock copolymers in experiments.