Charge-mosaic membrane from gamma-irradiated poly(styrene-butadiene-4-vinylpyridine) triblock copolymer

Poly(styrene-butadiene-4-vinylpyridine) triblock copolymers were prepared from styrene (S), butadiene (B), and 4-vinylpyridine (P) by sequential anionic polymerization with n-butyllithium as initiator and benzene as solvent. The triblock copolymer was characterizated by gel-permeation chromatography (GPC), transmission electron microscopy (TEM), and viscoelastic spectrometry. Films of the triblock copolymer cast from solution in mixtures of chloroform and n-butyraldehyde were subjected to gamma-ray irradiation to form cross-linked networks, Cationic and anionic groups were introduced by sulfonation and quater-nization to obtain charge-mosaic membranes. The resulting membrane had substantial cation-exchange and anion-exchange capacities. The membranes were very permeable to electrolyte (J_KCI = 2.10×10^?8 mol/cm² s). © 1993 John Wiley & Sons, Inc.     

Adsorption properties of amidoximated porous acrylonitrile/methyl acrylate copolymer beads for Ag (I)

Porous a crylonitrile (AN)/methyl acrylate (MA) copolymer beads were synthesized by suspended emulsion polymerization and amidoximated for the purpose of Ag⁺ adsorption. Optimum amidoximation temperature and time were determined by following the adsorption capacity for Ag⁺. The results showed that amidoximated AN/MA (AO AN/MA) with the amidoximation temperature 70°C and amidoximation time 20 hr had a relatively higher adsorption capacity for Ag⁺. The effect of pH on adsorption for Ag⁺ was studied; the highest adsorption capacity presented at pH 5.0. Adsorption kinetics and isotherms of AO AN/MA copolymer beads for Ag⁺ were also investigated. The kinetics data indicated that the adsorption process was governed by the film diffusion and followed both pseudo‐first‐order and pseudo‐second‐order rate model. The isotherms indicated that adsorption capacities increased with equilibrium concentration and temperature. The Langmuir model and Sips model could describe the isothermal process. Thermodynamic analysis revealed that the adsorption behaviors of Ag⁺ ions on AO AN/MA could be considered as endothermic and physical sorption process. Copyright © 2010 John Wiley & Sons, Ltd.     

Nanotechnological evaluation of protein adsorption on dialysis membrane surface hydrophilized with polyvinylpyrrolidone

Hydrophilizing synthetic polymer dialysis membranes with polyvinylpyrrolidone (PVP) play an important role for inhibition of protein adsorption on membrane surface. In the present study, the effect of PVP on protein adsorption was evaluated from a nano-scale perspective. Swelling behavior of PVP present on wet polysulfone (PS)/PVP film surfaces was observed by atomic force microscopy (AFM). Fibrinogen and human serum albumin (HSA) were immobilized on the tip of AFM probes, with which a force-curve between protein and wet PS/PVP film surface was measured by AFM while scanning in order to visualize two-dimensional protein adsorbability on film surfaces. Furthermore, HSA adsorbability on non-PVP containing PEPA dialysis membrane (FLX-15GW) and PVP containing PEPA dialysis membrane (FDX-150GW) was evaluated by the AFM force-curve method. As a result, PS/PVP film surface was completely covered with hydrated and swollen PVP at 5 wt% or more PVP content. Protein adsorbability on PS/PVP film surfaces decreased greatly with increasing content of PVP. The adsorption of HSA was inhibited by the presence of PVP on film surfaces more significantly than that of more hydrophobic fibrinogen. HSA adsorbability on wet FLX-15GW dialysis membrane surface was 428 ± 174 pN whereas that on wet FDX-150GW dialysis membrane surface was 42 ± 29 pN.     

Effect of crystallization on the morphologies of block copolymer/homopolymer blends cast in an electric field

Blends of polystyrene (PS) and poly(styrene-b-ethylene oxide) (PS-b-PEO) were cast from a ternary solvent mixture containing 85% toluene, 10% tetrahydrofuran, and 5% methanol under conditions that favor crystallization of the PEO phase. Electric fields (2–14 kV/cm) were applied during casting to explore the possibility of morphology control by the field. It was observed that films cast in the absence of an electric field, in the temperature range of 0–25°C, from solutions initially cooled to 0°C were translucent. Their transmission electron micrographs exhibited thread-like, fibrillar structures. Micrographs of films cast in dc fields of 2–14 kV/cm at 16.3 ± 0.4°C also showed fibrillar structures, with the fibrils in the presence of fields greater than 8 kV/cm being substantially oriented in the field direction. We suggest that the morphologies developed under these conditions result from crystallization from preexisting crystal nuclei in the cooled solutions with the fibrillar crystals being oriented by the electric field. This method provides a possible way of processing anisotropic polymer blends. © 1996 John Wiley & Sons, Inc.     

Grafting by in situ coupling of epoxy groups of a living copolymer with an anionic living polymer

A tetrahydrofuran (THF) solution of the living random copolymer of methyl methacrylate (MMA) and glycidyl methacrylate (GMA) was prepared by the living anionic copolymerization of the two monomers, using 1,1‐diphenylhexyllithium (DPHLi) as initiator, in the presence of LiCl ([LiCl]/[DPHLi]₀ = 3), at −50°C. The copolymer thus obtained has a controlled composition and molecular weight and a narrow molecular weight distribution. By introduction of an anionic living polystyrene (poly(St)) or anionic living polyisoprene (poly(Is)) solution into the above system at −30°C, a coupling reaction took place and a graft copolymer with a polar backbone and nonpolar side chains was produced. The solvent used in the preparation of the living poly(St) or poly(Is) affects the coupling reaction. When benzene was the solvent, a graft copolymer of high purity, controlled graft number and molecular weight, and narrow molecular weight distribution (M_w/M_n = 1.11–1.21) was obtained. In the coupling reaction, the living poly(St) reacted only with the epoxy groups and not with the carbonyls of the backbone polymer. © 1999 John Wiley & Sons, Inc. J Polym Sci A: Polym Chem 37: 105–112, 1999     

Adsorption Behavior of Metal Ions by Amidoxime Chelating Resins

In this work, the acrylonitrile (AN) – divinylbenzene (DVB) –methylacrylate (MA) resin was synthesized via suspension polymerization in the presence of toluene as diluent, and benzoylperoxide (BPO) as initiator. The effect of MA, toluene and alkaline treatment on the exchange capacity of the resin were investigated. The results showed that the anion exchange capacity decreased with an increase in the amount of MA, while alkaline treatment had no significant effect. Also, the cation exchange capacity increased with an increase in the amount of hydrophilic agent and reached a maximum point. The sorption equilibrium was achieved relatively fast within 40 mins, and the resin exhibited affinity towards lead (II), copper (II) and in particular uranium (VI). The adsorption of uranium was directly depended up on the pH value. Furthermore, the macroreticular chelating resin, containing amidoxime group had higher adsorption of uranium (VI) in comparison to other metal ions studied. Finally, the alkaline treatment enhanced the potential for much faster adsorption characteristics and the highly porous chelating resin provided a more favorable pore structure for the rapid rate of diffusion of metal ions.     

Poly(phenylene oxide) copolymer anion exchange membranes

Poly(phenylene oxide) block and random copolymers are synthesized by oxidative polymerization of 2,6-dimethylphenol and 2,6-diphenylphenol for potential alkaline exchange membrane application. The copolymers are functionalized on the methyl substituted repeat units through a two-step process to produce pendent quaternary ammonium cationic groups. The amount of quaternary ammonium cations and the ion exchange capacity are quantified through titration measurements. Ionic conductivity of the copolymer membranes is measured by electrochemical impedance spectroscopy. Block copolymers show increased bromide conductivity at higher ion exchange capacities compared with the random copolymer analogs. The bromide conductivity for a block copolymer film with an ion exchange capacity of 1.27 mequiv/g reaches 26 mS/cm at 90 °C and 95% relative humidity. The hydroxide conductivity for the same film was measured to be 84 mS/cm at 80 °C and 95% relative humidity. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2013, 51, 1770–1778, 2013     

聚烯丙基胺硅胶复合材料的合成及其吸附性能

氯丙基三氯硅烷-硅胶;聚烯丙基胺硅胶复合材料的合成及其吸附性能     

Bulk modification of PDMS microchips by an amphiphilic copolymer

A simple and rapid bulk-modification method based on adding an amphiphilic copolymer during the fabrication process was employed to modify PDMS microchips. Poly(lactic acid)-poly(ethylene glycol) (PLA-PEG) was used as the additive substance. Compared to the native PDMS microchips, both the contact angle and the EOF of the bulk-modified PDMS microchips decreased. The effects of the additive loading and the pH on the EOF were investigated in detail. The bulk-modified PDMS microchips exhibited reproducible and stable EOF behavior. The application of the bulk-modified PDMS microchips was also studied and the results indicated that they could be successfully used to separate amino acids and to suppress protein adsorption.     

Micellization to gelation of a triblock copolymer in water: Thermoreversibility and scaling

Aqueous solutions of a poly(ethylene oxide)–poly(propylene oxide)–poly(ethylene oxide) triblock copolymer, Pluronic F108 (PEO₁₃₃PPO₅₀PEO₁₃₃), ranging from 1 to 35 wt %, were studied with differential scanning microcalorimetry and rheology. The thermoreversible micellization and gelation were examined through a heating process and a subsequent cooling process at a fixed rate of 1 °C/min. The critical micellization temperature (CMT), determined by the onset temperature of the endothermic peak in the heating process, was a decreasing function of the F108 concentration. A small secondary endothermic peak appeared only when the polymer concentration was 22.5 wt % or higher, indicating that there was a sol–gel transition but that the gelation was a nearly athermic process. Upon heating, an abrupt increase was observed in both the dynamic storage modulus (G′) and dynamic loss modulus (G″) within a narrow temperature range. T_G′, the temperature for the transition in G′, was a linear decreasing function of the polymer concentration and different from CMT. T_G′ tended to approach CMT with an increasing F108 concentration. Beyond this transition, G′ reached a plateau, and the plateau increased in height and broadened with the polymer concentration. The value of G′ at 70 °C (G′₇₀) could be approximately scaled with concentration c by G′₇₀ ∝ c^7.3. In addition, the definition for a gel to obey G′ > G″ was valid only when c was greater than 22.5 wt %, and this was in agreement with the secondary endothermic peak found with differential scanning calorimetry. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 2014–2025, 2004     

明胶-环氧聚醚胺交联膜的合成及其对重金属离子的吸附性能

首先利用聚乙二醇二缩水甘油醚(PEO-DE)、聚二甲基硅氧烷二缩水甘油醚(PDMSDE)与无水哌嗪以1∶1∶1的物质的量之比反应合成环氧封端的聚醚胺(ePEA),然后将ePEA分散在水相中与明胶混合,浇铸固化成膜。利用红外光谱(FT-IR)、X射线衍射(XRD)、示差扫描量热法(DSC)和原子吸收光谱(AAS)等手段研究了明胶-环氧聚醚胺交联膜的结构和离子吸附性能。结果表明,与纯明胶膜相比,交联膜中的环氧聚醚胺与明胶之间出现了新的化学交联结构,在水溶液中的稳定性提高;交联膜对Cu2+、Pb2+、Cd2+均有一定的吸附作用,并且吸附能力随着ePEA含量的增加而增加;吸附过程符合二级动力学模型和Langmuir等温模型。     

Heat capacity of water in poly(methyl methacrylate) hydrogel membrane for an artificial kidney

The heat capacities of a poly(methyl methacrylate) hydrogel membrane for an artificial kidney have been determined over the range of temperatures from 228 to 298 K as a function of water content. At least two kinds of water were found: freezable water and nonfreezable water. The partial specific heat capacities of both waters were calculated from the dependence of heat capacity of the hydrogel on the water content. The heat capacities of freezable water were estimated to be 1.04 cal g⁻¹ K⁻¹ at 298 K and 0.47 cal g⁻¹ K⁻¹ at 228 K. The mobility must therefore be similar to that of bulk water at 298 K, though the melting temperature was lower than that of bulk water. Consequently, the freezable water was not assigned to bound water but to pore water for which the melting temperature was depressed due to interfacial tension. On the other hand, the heat capacities of nonfreezable water were estimated to be 1.02 cal g⁻¹ K⁻¹ at 298 K and 1.06 cal g⁻¹ K⁻¹ at 228 K. The mobility of the water would be similar to that of free water at both 298 and 228 K. © 1995 John Wiley & Sons, Inc.     

Membrane Preparation of Polysulfonic Acid Complexes by Layer-by-Layer Adsorption

Summary: The water-insoluble, thermostable and homogeneous polymer complex membrane formation of polysulfonic acids was examined by modifying the preparation conditions of the layer-by-layer adsorption method of the acid and base polymers. The complexation of poly(4-styrenesulfonic acid) in the 0.15 unit mM solution with poly(allylamine) gave a polymer complex membrane on a gold substrate in which one polymer layer was formed with a thickness of 1 nm. Properties including the proton conductivity of the membrane suggested possible applications of the polymer complex membrane.     

聚(N-对乙烯基苄基二甲胺)树脂对苯酚的吸附性能

采用二甲胺为功能化试剂,化学修饰氯甲基化苯乙烯-二乙烯基苯共聚物合成了大孔交联聚(N-对乙烯基苄基二甲胺)树脂,测得树脂的氯含量由4.2mmol/g降低到0.24mmol/g,树脂的弱碱交换量为4.0mmol/g,说明氯甲基化苯乙烯-二乙烯基苯共聚物发生胺化反应完全。在水溶液中,测定了大孔交联聚(N-对乙烯基苄基二甲胺)树脂对苯酚的吸附等温线,发现吸附平衡数据符合Freundlich等温吸附方程,相关系数大于0.99。计算得到在吸附量为15、20和25mg/g时,等量吸附焓在-20.81~-30.74kJ/mol范围内,吸附自由能和吸附熵均小于0,说明吸附过程中存在氢键作用,吸附是自发、混乱度变小的过程。比较树脂对水溶液中苯酚、对硝基苯酚和对硝基甲苯的吸附性能以及树脂对水、环己烷、乙醇和乙酸乙酯溶液中苯酚的吸附性能,进一步说明大孔交联聚(N-对乙烯基苄基二甲胺)树脂对水溶液中苯酚的吸附是基于疏水作用和氢键作用协同的机理。     

A novel pathogen detection system based on high‐resolution CE‐SSCP using a triblock copolymer matrix

Although CE‐SSCP analysis combined with 16S ribosomal RNA gene‐specific PCR has enormous potential as a simple and versatile pathogen detection technique, low resolution of CE‐SSCP causes the limited application. Among the experimental conditions affecting the resolution, the polymer matrix is considered to be most critical to improve the resolution of CE‐SSCP analysis. However, due to the peak broadening caused by the interaction between hydrophobic moiety of polymer matrices and DNA, conventional polymer matrices are not ideal for CE‐SSCP analysis. A poly(ethyleneoxide)‐poly(propyleneoxide)‐poly(ethyleneoxide) (PEO‐PPO‐PEO) triblock copolymer, with dynamic coating ability and a propensity to form micelles to minimize exposure of hydrophobic PPO block to DNA, can be an alternative matrix. In this study, we examined the resolution of CE‐SSCP analysis using the PEO‐PPO‐PEO triblock copolymer as the polymer matrix and four same‐sized DNA fragments of similar sequence content. Among 48 commercially available PEO‐PPO‐PEO triblock copolymers, three were selected due to their transparency in the operable range of viscosity and PEO₁₃₇PPO₄₃PEO₁₃₇ exhibited the most effective separation. Significant improvement in resolution allowed discrimination of the similar sequences, thus greatly facilitated CE‐SSCP analysis compared to the conventional polymer matrix. The results indicate that PEO‐PPO‐PEO triblock copolymer may serve as an ideal matrix for high‐resolution CE‐SSCP analysis.     

Surface charge modulation of poly(ethylene glycol)–poly( , -lactide) block copolymer micelles: conjugation of charged peptides

Block copolymer micelles with aldehyde functionality were prepared in aqueous medium by dialyzing the N,N-dimethylacetamide solution of α-acetoxy-poly(ethylene glycol)-poly( , -lactide) block copolymer (acetal-PEG–PDLLA) against water, followed by mild acid treatment to convert the acetal moiety of the micelle to the aldehyde group. Peptidyl ligands (phenylalanine (Phe) and tyrosyl–glutamic acid (Tyr–Glu)) were then chemically conjugated to the micelle through Schiff base formation and successive reductive amination using NaBH₃CN. Micelles with peptidyl ligands thus prepared have a size of approximately 40 nm with extremely narrow distribution (μ₂/ ²<0.1) based on cumulant analysis of dynamic light scattering. A maximum 53% of the PEG-chain end of the micelle could be converted into peptidyl groups. Zeta potential values of Tyr–Glu derivatized micelles were well correlated with the amount of conjugated ligands, controllable over the range of 0 to−9 mV in sodium phosphate buffer (pH 7.4, 10 mM). These micelles with peptidyl ligands may have a utility for exploring the effect of the surface charge on the pharmacokinetic behavior of particulate systems as well as for modulated drug delivery where cellular peptidyl receptors play a substantial role.     

Electroreductive polymerization of phenylmethyldichlorosilane in a divided cell using a neutral membrane

Electrochemical formation of poly(phenylmethylsilane) in a divided cell containing a Teflon® neutral membrane was studied. The electrolysis of dichlorosilanes was carried out in a solution containing tetrahydrofuran + hexamethylphosphoramide as the solvent, tetrabutylammonium perchlorate as the support electrolyte and stainless steel as the cathode, with Pt and graphite as the resistant anodes or stainless steel as the sacrificial anode. Polysilanes with a number-average molecular weight in the range from 2,600 to 130,000 g/mol were obtained, depending on the conditions used.     

Evaluation of asymmetrical structure dialysis membrane by tortuous capillary pore diffusion model

The tortuous capillary pore diffusion model (TCPDM) has been used for estimating diffusive and pure water permeability from simple structure parameters such as pore diameter, surface porosity, wall thickness and tortuosity. The validity of this model for evaluation of homogeneous membrane has been already confirmed. Recently, there is a trend toward the use of asymmetrical dialysis membranes made of synthetic polymer such as poly(acrylonitrile) (PAN), polysulfone (PS) and a polyethersulfone polyarylate (PEPA) blend polymer. The purpose of the present study is to apply the TCPDM to evaluation of commercially available hollow-fiber dialysis membranes with asymmetrical structures by simplifying them to a double-layer membrane. The TCPDM is capable of estimating pore tortuosity of asymmetrical dialysis membranes having skin and supporting layers from data on membrane thickness, pore diameter, pure water permeability and water content. Values for diffusive permeability obtained by the TCPDM are in a good agreement with experimental data. This TCPDM model is useful for evaluation of not only homogeneous membrane but also asymmetrical membrane.     

大孔交联酰胺类聚合物对苯酚氢键吸附机理的研究

大孔交联酰胺类聚合物是一类同时能提供氢键的给体(—NH—)和氢键的受体(—C O)的功能高分子材料。将D392乙酰化制得大孔交联聚(N-对乙烯基苄基乙酰胺)(PS-CH2NHCOCH3),并对其化学结构进行表征;测定了它在非水体系中对苯酚的吸附等温线,计算出不同吸附量时对应的吸附焓。结果表明,合成的大孔交联PS-CH2NHCOCH3在环己烷中对苯酚的吸附量大,吸附选择性高,排除了吸附过程的疏水作用及范德华力的影响因素,证明其吸附机理为氢键吸附。     

Porous poly(vinylidene fluoride) membrane modified with hyperbranched poly(amine‐ester)

Poly(vinylidene fluoride) (PVDF) membranes were hydrophilic modified with hydroxyl group terminated hyperbranched poly(amine‐ester) (HPAE). Fourier transform infrared spectroscopy (FT‐IR) was used to study the chemical change of PVDF membranes. X‐ray photoelectron spectroscopy (XPS) indicated that some HPAE molecules were retained in PVDF membrane through polymer chain coiling. The presence of HPAE would improve the hydrophilicity of PVDF membrane. Scanning electron microscopy (SEM) was employed to characterize the morphology of different membranes. The thermodynamic stability for PVDF/DMAc/HPAE/Water system was characterized by the determination of the gelation values. Precipitation kinetics for PVDF/DMAc/HPAE/Water system was studied by precipitation time measurement. The water contact angle indicated that the hydrophilicity and the biocompatibility corresponding to protein adsorption of PVDF membrane were improved significantly after blending with hydrophilic HPAE molecules. Copyright © 2011 John Wiley & Sons, Ltd.