电子辐照及再结晶P(VDF-TrFE)共聚薄膜红外光谱研究

利用傅立叶变换红外光谱(FT-IR)研究聚偏氟乙烯与聚三氟乙烯共聚薄膜[P(VDF0.80-TrFE0.20)]的电子辐照和再结晶处理过程中分子链构型变化和化学变化, 为深入探讨辐照的改性机理提供依据. 研究发现, 辐照后薄膜分子链全反构型百分含量随吸收剂量增大而迅速减少, TG构型和T3G构型百分含量显著增多. 而当吸收达一定剂量时, 三种构型相对含量基本不再变化, 表明高剂量辐照时样品极性回升不依赖分子链构型中全反型的含量的增多, 而是和高交联度的边界效应有关. 再结晶过程中分子链构型变化恰好和辐照效应产生的变化相反, 并且形成了更加稳定的C=C共轭结构.     

Dynamic mechanical properties of extruded rods of poly(dimethylsilylene‐co‐methyl‐n‐propylsilylene)

Tractable polysilanes were prepared by the copolymerization of a methyl‐n‐propylsilylene (MP) unit into poly(dimethylsilylene), which neither dissolves in common solvents nor melts before decomposition. Although poly(dimethylsilylene‐co‐methyl‐n‐propylsilylene) has poor solubility in the composition range of the dimethylsilylene (DM) unit to the MP unit (DM/MP = 7/3 ∼ 9/1), the copolymers form the columnar mesophase at elevated temperatures. Highly oriented rods were prepared via the extrusion of the copolymers with a circular tube die in a temperature range in which the transition to the columnar mesophase began to occur (70°C when DM/MP = 7/3 and 8/2 and 120°C when DM/MP = 9/1). The extruded rods were characterized in detail by dynamic viscoelasticity and wide‐angle X‐ray diffraction (WAXD) to clarify the structure–mechanical‐property relationship. The orientation functions of the extruded rods were determined by the azimuthal intensity distribution of the WAXD reflection. The orientation function and dynamic storage modulus increased with an increasing extrusion ratio. The dynamic storage modulus at −150°C was 8 ∼ 10 GPa at the highest extrusion ratio and correlated well with the crystal orientation function. The dynamic storage modulus at room temperature was lowered by the structural relaxations at −100 ∼ +30°C, which corresponded to the molecular motion of the rigid molecular chains of the copolymer and the local molecular motion of the MP unit. © 2000 John Wiley & Sons, Inc. J Polym Sci B: Polym Phys 38: 698–706, 2000     

Synthesis of Poly(IB‐co‐VBDC)‐g‐PMMA via Photo‐initiated Free Radical Graft Polymerization

Abstract

Photoinitiated free radical graft polymerization of methyl methacrylate (MMA) with poly[isobutene‐co‐(4‐vinyl benzyl N,N‐diethyldithiocarbamate)] [poly(IB‐co‐VBDC)] as macromolecular iniferter was investigated. The polymerization proceeds to give a high yield graft copolymer, however it was observed that even in the early stage of the polymerization there formed an insoluble polymer. In the presence of tetraethylthiuram disulfide (TETD) the gel fraction of the yield graft copolymer was drastically reduced and the polymerization was retarded as well. When the [TETD]/[VBDC] increased from 0 to 1.0, the gel fraction of the graft copolymer decreased from 33.2% to 1.6% (wt) while the fraction of the homopolymer of the MMA increased from 4.5% to 10.5% (wt). With the increasing of the UV irradiation time, both the MMA conversion and the molecular weight of the graft copolymer increased readily.     

Acid-catalyzed copolymerization of aspartic acid with ω-amino acid. -Biodegradability and Ca2+ chelating ability of poly(aspartic acid -Co- ω-amino acid)-

The polycondensation of L-aspartic acid (1) with various ω-amino acids (2) using phosphoric acid catalyst produced poly(succinimide-co-ω-amino acid)s (3), which was followed by alkali hydrolysis to poly(aspartic acid-co-ω-amino acid) (4). The Ca²⁺ chelating abilities of 4 depended on the content of comonomer unit in the copolymer and on the kind of amino acids. For the copolymer using 11-aminoundecanoic acid (2d) as a comonomer, the Ca²⁺ chelating ability was higher than that of poly(sodium acrylate). For poly(aspartic acid-co-6-aminocaproic acid) (4c), there was a tendency to increase according to the increase of 6-aminocaproic acid (2c) unit in the copolymer. The biodegradability of the copolymer in the case of 2c as a comonomer, evaluated by TOC measurement, was 63%, which was the highest degradability among the copolymers having different methylen length. The biodegradability of 4c decreased with increasing the 2c unit in 4c.     

PSF-g-P(PEGMA)的合成及其共混超滤膜的制备与性能研究

以氯甲基化双酚A型聚砜(PSF-CH2Cl)为大分子引发剂,通过原子转移自由基聚合(ATRP)法合成了以聚砜(PSF)为疏水主链、聚(聚乙二醇单甲醚甲基丙烯酸酯)[P(PEGMA)]为亲水侧链的梳状两亲性共聚物PSF-g-P(PEGMA).FT-IR和1H-NMR的表征结果证实了两亲性共聚物的生成.将PSF-g-P(PEGMA)与PSF进行共混,通过浸没沉淀法制备了共混超滤膜.研究发现,引入5 wt%的PSF-g-P(PEGMA),共混膜的孔隙率和平均孔径分别从65.9%和0.08μm提高到81.9%和0.18μm;将共混膜于90℃热水中浸泡24 h后,膜表面O/S从14.63提高到17.16;共混膜的亲水性和抗牛血清蛋白(BSA)吸附性能显著提升.     

Synthesis of block copolymer-stabilized Au-Ag alloy nanoparticles and fabrication of poly(methyl methacrylate)/Au-Ag nanocomposite film

[Poly(2-(N,N-dimethylamino)ethyl methacrylate)]-b-poly(methyl methacrylate)-b-[poly(2-(N,N-dimethylamino)ethyl methacrylate)] (M(n)=45,000; 20K-5K-20K; PDI = 1.2) block copolymer surfactant stabilized amphiphilic gold-silver alloy nanoparticles (Au-Ag(PDMA-b-PMMA-b-PDMA)) has been synthesized in both water and in organic medium. The block copolymer stabilized pre-made alloy nanoparticles were successfully dispersed in hydrophobic poly(methyl methacrylate) homopolymer matrix (PMMA) of molecular weight 30,000. The successful synthesis of alloy nanoparticles was accessed by Transmission Electron Microscope (TEM), Energy Dispersed X-ray (EDX), and UV-visible spectrophotometric analysis. The surface functionality of the nanoparticles was confirmed by quantitative determining the grafting density of polymer chain around the nanoparticle surface using combination of thermo gravimetric (TGA) and TEM analysis. The hydrodynamic diameter of the alloy particles including the polymer chains was obtained from dynamic light scattering measurement (DLS). The mechanism of synthesis of high concentration of Au-Ag alloy particles from HAuCl(4) and AgNO(3) (in presence of Cl(-) from reduction of gold salt) metal particles precursors and the successful preparation of poly(methyl methacrylate)/gold-silver nanocomposite films have been discussed.     

Graft copolymerization induced by thermal reactions of the binary alkali salts of poly(carboxylic acid)–brominated carboxylic acid in bulk

Thermal reactions of the binary alkali salts of poly(carboxylic acid)–brominated carboxylic acid such as sodium or potassium poly(4-vinylbenzoate)-2-bromopropanoate [Na or K (PVBA-2-BPA)] in bulk were investigated. A methanol solution of binary acids was prepared by fixing the molar ratio of the repeating unit of polymeric acid to the fraction of brominated carboxylic acid. The binary salts were prepared by the neutralization of the binary acid solution. The product of the thermal reaction followed by esterification was identified as a graft copolymer containing PVBA in the main chain and polylactic acid in the side chain. The reaction of 1/15 K (PVBA-2-BPA) at 120 °C for 2 h yielded the highest percentage of grafting (300%). The grafting proceeded gradually for the initial 2 h and then somewhat. Reactivity of the K salt was higher than that of the corresponding Na salt. The thermal reaction of 1/10 K [polymethacrylate-2-BPA (PMA-2-BPA)] at 120 °C for 2 h also yielded a graft copolymer, and the percentage of grafting was 300%. However, reaction temperatures higher than 120 °C caused homopolycondensation of K 2-BPA prior to grafting, and homopolycondensation occurred prior to grafting in the reaction with Na (PMA-2-BPA). © 2001 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 39: 1877–1885, 2001     

无卤阻燃丙烯腈共聚物的制备及性能

以K₂S₂O₈-NaHSO₃ 氧化还原体系为引发剂, 采用水相沉淀自由基聚合法合成丙烯腈(AN)-醋酸乙烯酯(VAc)无规共聚物[P(AN-co-VAc)], 然后在KOH水溶液中进行P(AN-co-VAc)中VAc单元的选择性水解, 再与磷酸和尿素进行磷酰化反应, 制备无卤阻燃丙烯腈共聚物. 用核磁共振氢谱(¹H NMR)、傅里叶变换红外光谱(FTIR)、差示扫描量热(DSC)和热重分析(TGA)对聚合物结构及热性能进行表征, 用凝胶渗透色谱(GPC)测定了P(AN-co-VAc)的分子量及其分布, 并利用FTIR和扫描电子显微镜(SEM)对无卤阻燃丙烯腈共聚物的炭残渣进行分析. 结果表明, VAc与AN发生共聚反应, 制得了P(AN-co-VAc), 随着KOH水溶液pH值的增大, P(AN-co-VAc)中VAc单元迅速水解; DSC分析结果表明, 随着共聚物中VAc单元含量的增大, 共聚物的环化放热分解峰值温度(T_p)增大, 当VAc单元的质量分数为25%时, T_p最大值高达328 ℃, 而阻燃丙烯腈共聚物的T_p高达340 ℃; TGA分析结果表明, 阻燃共聚物在800 ℃时的炭残渣量高达55%以上, 远高于P(AN-co-VAc)的41%, 具有良好的成炭性; 炭残渣的FTIR及SEM结果表明, 阻燃丙烯腈共聚物的阻燃属于凝聚相阻燃.     

Effect of Comonomer‐Unit Compositional Distribution on Thermal and Crystallization Behavior of Bacterial Poly[(3‐hydroxybutyrate)‐co‐(3‐mercaptopropionate)]

The physical properties of novel sulfur‐containing biopolymers, poly[(3‐hydroxybutyrate)‐co‐(3‐mercaptopropionate)]s [P(3HB‐co‐3MP)s], have been investigated in detail by¹H and ¹³C NMR spectroscopy, wide‐angle X‐ray diffraction (WAXD) analysis, DSC, and FT‐IR spectroscopy. Based on a solvent/non‐solvent (chloroform/heptane) fractionation method, an original P(3HB‐co‐3MP) sample with 3MP unit content of 16.3 mol‐% was fractionated into eight fractions with 3MP unit content ranging from 10.3 to 37.2 mol‐% and number‐average molecular weight from 0.4 × 10⁵ to 2.9 × 10⁵. The thermal and crystallization behavior were found to be greatly affected by the comonomer‐unit composition and its distribution. Furthermore, the 3MP comonomer unit was found to be included in the crystalline phase in some fractions.

     

Biosynthesis and compositional regulation of poly[(3-hydroxybutyrate)-co-(3-hydroxyhexanoate)] in recombinant ralstonia eutropha expressing mutated polyhydroxyalkanoate synthase genes

A new strategy for bacterial polyhydroxyalkanoate (PHA) production by recombinant Ralstonia eutropha PHB(-)4 harboring mutated PHA synthase genes (phaC(Ac)) from Aeromona caviae was investigated. The strain harboring wild-type phaC(Ac) gene produced a PHA copolymer consisting of (R)-3-hydroxybutyrate and (R)-3-hydroxyhexanoate [P(3HB-co-3HHx)] with 3.5 mol-% of 3HHx fraction from soybean oil. When the mutants of phaC(Ac) gene were applied to this production system, 3HHx fraction in copolymers was varied in the range of 0-5.1 mol-%. Thus, the regulation of PHA copolymer compositions has been achieved by the use of mutated PHA synthase genes.     

Accumulation of biopolymers in activated sludge biomass

In this study, activated sludge bacteria from a conventional wastewater treatment process were induced to accumulate polyhydroxyalkanoates (PHAs) under different carbon-nitrogen (C:N) ratios. As the C:N ratio increased from 20 to 140, specific polymer yield increased to a maximum of 0.38 g of polymer/g of dry cell mass while specific growth yield decreased. The highest overall polymer production yield of 0.11 g of polymer/g of carbonaceous substrate consumed was achieved using a C:N ratio of 100. Moreover, the composition of polymer accumulated was dependent on the valeric acid content in the feed. Copolymer poly (3-hydroxybutyrate-co-3-hydroxyvalerate) [P(3HB-co-3HV)] was produced in the presence of valeric acid. The 3-hydroxyvalerate (3HV) mole fraction in the copolymer was linearly related tovaleric content in the feed, which reached a maximum of 54% when valeric acid was used as sole carbon source. When the 3HV U in the polymer increased from 0–54 mol%, the melting temperature decreased from 178° to 99°C. Thus, the composition, and hence the mechanical properties, of the copolymer produced from activated sludge can be controlled by adjusting the mole fraction of valeric acid in the feed medium.     

Preparation and characterization of heteroarm H‐shaped terpolymers by combination of reversible addition‐fragmentation transfer polymerization and ring‐opening polymerization

Heteroarm H‐shaped terpolymers, [(poly(L ‐lactide))(polystyrene)]poly(ethylene oxide)[(polystyrene)(poly(L ‐lactide))], [(PLLA)(PS)]PEO[(PS)(PLLA)], in which PEO acts as a main chain and PS and PLLA as side arms, have been successfully prepared via combination of reversible addition–fragmentation transfer (RAFT) polymerization and ring‐opening polymerization (ROP). The first step is the synthesis of the PEO capped with one terminal dithiobenzoate group and one hydroxyl group at every chain end, [(HOCH₂)(PhC(S)S)]PEO[(S(S)CPh)(CH₂OH)] from the reaction of carboxylic acid with ethylene oxide. Then, the RAFT polymerization of styrene (St) was carried out using [(HOCH₂)(PhC(S)S)]PEO[(S(S)CPh)(CH₂OH)] as RAFT agent and AIBN as initiator, and the triblock copolymer, [(HOCH₂)(PS)]PEO[(PS)(CH₂OH)], was formed. Finally, the heteroarm H‐shaped terpolymers, [(PLLA)(PS)]PEO[(PS)(PLLA)], were produced by ROP of LLA, using triblock copolymer, [(HOCH₂)(PS)]PEO[(PS)(CH₂OH)], as macroinitiator and Sn(Oct)₂ as catalyst. The target products and intermediates were characterized by ¹H NMR spectroscopy and gel permeation chromatography. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 789–799, 2007     

Synthesis and micellization of amphiphilic poly(sebacic anhydride)–poly(ethylene glycol)–poly(sebacic anhydride) block copolymers

Amphiphilic biodegradable block copolymers [poly(sebacic anhydride)–poly(ethylene glycol)–poly(sebacic anhydride)] were synthesized by the melt polycondensation of poly(ethylene glycol) and sebacic anhydride prepolymers. The chemical structure, crystalline nature, and phase behavior of the resulting copolymers were characterized with ¹H NMR, Fourier transform infrared, gel permeation chromatography, and differential scanning calorimetry. Microphase separation of the copolymers occurred, and the crystallinity of the poly(sebacic anhydride) (PSA) blocks diminished when the sebacic anhydride unit content in the copolymer was only 21.6%. ¹H NMR spectra carried out in CDCl₃ and D₂O were used to demonstrate the existence of hydrophobic PSA domains as the core of the micelle. In aqueous media, the copolymers formed micelles after precipitation from water‐miscible solvents. The effects on the micelle sizes due to the micelle preparation conditions, such as the organic phase, dropping rate of the polymer organic solution into the aqueous phase, and copolymer concentrations in the organic phase, were studied. There was an increase in the micelle size as the molecular weight of the PSA block was increased. The diameters of the copolymer micelles were also found to increase as the concentration of the copolymer dissolved in the organic phase was increased, and the dependence of the micelle diameters on the concentration of the copolymer varied with the copolymer composition. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 1271–1278, 2006     

Organic vapor sensing properties of copolymer Langmuir-Blodgett thin film sensors

In this study, a novel poly[Styrene (ST)-co-Glycidyl Methacrylate (GMA)] copolymer material is used to fabricate Langmuir-Blodgett (LB) thin films and investigate organic vapor sensing properties. Quartz Crystal Microbalance (QCM) system is used to investigate gas sensing performance of copolymer LB films during exposure to Volatile Organic Compounds (VOCs). The poly[Styrene (ST)-co-Glycidyl Methacrylate (GMA)] LB thin film sensor sensitivities are determined to be between 0.12 and 0.25 Hz ppm^?1. Detection limits of the copolymer LB thin film are found to be between 23 and 49 ppm against organic vapors. The copolymer LB thin films are more sensitive to chloroform than other vapors used in this study. The results demonstrated that the poly[Styrene (ST)-co-Glycidyl Methacrylate (GMA)] copolymer material is promising as a organic vapor sensing device at room temperature.     

Synthesis and conformation of poly(L-azetidine-2-carboxylic acid-L-proline) and poly([L-proline]3-L-azetidine-2-carboxylic acid)

The synthesis, characterization, and conformational assessment of poL y(L -Aze-L -Pro) and poly[(L -Pro)₃-L -Aze] are reported. The polymers were prepared by using the pentachlorophenol active ester as the polymerizable tetrapeptide derivatives. The copolymer, poly(L -Aze-L -Pro), assumes a Form II helix in polar solvents, and is converted into a form I-like helix at a critical solvent composition of ethanol to trifluoroethanol. The CD spectrum of this Form I-like conformation of poly(L -Aze-L -Pro) is similar to that of poly(trans-5-isopropyl-L -proline), indicating that the rigid four-membered ring at the alternating position can lock in the structure by a mechanism similar to that of a bulky substituent at the trans-5-position of proline. The helix conformation of this copolymer was unfolded in a 0.2M CaCl₂ aqueous solution. In contrast to poly(L -Aze-L -Pro), the copolymer of poly[(L -Pro)₃-L -Aze] contains both cis and trans peptide bond geometry when dissolved in a 90:10 ETOH-H₂O mixture. The conversion of the mixed conformation of poly[(L -Pro)₃-L -Aze)] into a polyproline Form II-like structure occurred in highly polar solvent environments such as water.     

Synthesis and characterization of thermally crosslinked polyimide with second-order nonlinear optical chromophore

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Synthesis of graft copolymers having phospholipid polar group by macromonomer method and their properties in water

Water-soluble graft copolymers with phospholipid polar group were synthesized by the macromonomer method and their properties in water were investigated by surface tension and fluorescence spectroscopic measurements. At first, 2-methacryloyloxyethyl phosphorylcholine (MPC) was polymerized in the presence of 3-mercapt propionic acid as a chain transfer agent and carboxyl group-terminated oligo (MPC) was obtained. The oligo (MPC) reacted with glycidyl methacrylate to convert the carboxyl group to a polymerizable methacryloyl group. The MPC macromonomer obtained was copolymerized with hydrophobic n-butyl methacrylate (BMA) and a graft copolymer was obtained. The graft copolymer, poly(MPC-graft-BMA), was water-soluble when the MPC unit mole fraction was above 0.40. The surface tension of the aqueous solution of poly(MPC-graft-BMA) did not depend on the polymer concentration below 0.1 wt %. This tendency was the same as that which appeared in aqueous poly(MPC) solution. The fluorescence intensity of hydrophobic probes observed in an aqueous solution of the poly (MPC-graft-BMA) was also the same level as that observed in the case of poly(MPC). These results clearly indicated that the poly(MPC-graft-BMA) took a domain structure like micelle in water, i.e., the hydrophobic poly(BMA) backbone was in the core part and the hydrophilic poly(MPC) chain formed the shell part of the micelle. © 1994 John Wiley & Sons, Inc.     

Synthesis of H‐shaped A3BA3 copolymer by methyl‐2‐nitrosopropane induced single electron transfer nitroxide radical coupling

Amphiphilic H‐shaped [poly(ethylene oxide)]₃‐polystyrene‐[poly(ethylene oxide)]₃(PEO₃‐PS‐PEO₃) copolymer was synthesized by 2‐methyl‐2‐nitrosopropane (MNP) induced single electron transfer nitroxide radical coupling (SETNRC) using PEO₃‐(PS‐Br) as a single precursor. First, the A₃B star‐shaped precursor PEO₃‐(PS‐Br) was synthesized by atom transfer radical polymerization (ATRP) using three‐arm star‐shaped PEO₃‐Br as macro‐initiator. Then, in the presence of Cu(I)Br/Me₆TREN, the bromide group at PS end was sequentially transferred into carbon‐centered radical by single electron transfer and then nitroxide radical by reacting with MNP in mixed solvents of dimethyl sulfoxide (DMSO)/tetrahydrofuran (THF), and in situ generated nitroxide radical could again capture another carbon‐centered radical by fast SETNRC to form target PEO₃‐PS‐PEO₃ copolymer. The MNP induced SETNRC could reach to a high efficiency of 90% within 60 min. After the product PEO₃‐PS‐PEO₃ was cleaved by ascorbic acid, the SEC results showed that there was about 30% fraction of product formed by single electron transfer radical coupling (SETRC) between carbon‐centered radicals. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011     

Evaluation of membranes of copolypeptide of γ-benzyl -glutamate and -glutamic acid for the permeability of anticancer drugs

The membranes of poly(γ-benzyl -glutamate-co- -glutamic acid) [P(BLG-LGA)] were prepared by saponification of poly(γ-benzyl -glutamate) (PBLG) membranes. The permeation of two anticancer drugs, 5-fluoro-uracil (5-fu) and 2-hydroxyethyl-oxy-methyl-5-fluoro-uracil (2-HEOM-5-Fu), through these membranes was studied. The results showed a sharp increase in permeability of the copolymer membranes compared to the PBLG membranes.     

Self-assembly of mixtures of block copolymers of poly(styrene-b-acrylic acid) with random copolymers of poly(styrene-co-methacrylic acid)

The effects of the addition of random copolymers of poly(styrene-co-methacrylic acid) [P(S-co-MAA)] on the self-assembly of block copolymers of poly(styrene-b-acrylic acid) (PS-b-PAA) are described. The effects of variation of five factors, including the MAA content, the weight fraction and molar mass of the P(S-co-MAA), the initial concentration of the mixture, and the length of the PAA segment in the block copolymer, were investigated. With increasing MAA content, the localization of the random copolymer in the aggregate changed from the core to the interface, which led to a morphological transition from spheres to vesicles. Vesicles, mixtures of vesicles and large spheres, and large spheres alone were formed with increasing weight fraction of the random copolymer. When the molar mass of the random copolymer was high, both rods and vesicles were observed at low water contents; otherwise, only vesicles were observed. The vesicle size increased (from 100 to 140 nm) with increasing initial polymer concentration, whereas the vesicle membrane thickness remained constant. The size of the vesicles prepared from the mixtures increased with water content but decreased with the length of PAA in the diblock.