聚对亚苯基二亚甲基薄膜的表面化学改性及其肝素化反应

采用化学气相沉积聚合(CVDP)法制备聚对亚苯基二亚甲基(PPX),再通过与酸酐的化学表面反应将丁酸酰基和马来酰基引入PPX薄膜的表面,制得表面带活性取代基的PPX.改性后的薄膜表面粗糙度略有增加,但仍旧维持在10nm以内.改性后的薄膜水接触角减小,减小幅度达到十几度,表面亲水性大幅度提高.丁二酸酐表面改性后薄膜的抗化学氧化时间不变,马来酸酐表面改性后薄膜的抗氧化时间略有下降,但抗氧化时间都大于30h,仍具有优异的抗化学氧化性能.丁酸酰基和马来酰基取代PPX肝素化反应后膜中的肝素含量在7μg/cm2左右,肝素化后薄膜的抗凝血性能得到明显提高.     

聚亚甲基绿的性质

在 10～ 6 0℃范围内 ,测定了聚亚甲基绿的循环伏安图和交流阻抗图 ,测定了循环伏安所用电解质溶液的电导率随温度的变化 .在不同温度下 ,聚亚甲基绿的循环伏安图上均有一阳极峰和一阴极峰 ,阳极峰和阴极峰的峰电流均随温度升高而增加 ,即电极反应速率随温度升高而增加 .交流阻抗的结果表明 ,聚亚甲基绿的电荷传递电阻Rct随温度升高而增大 .热重 (TG)实验表明聚亚甲基绿热失重是分三步进行的 ,聚合物在 2 6 3 .1℃时发生分解 .扫描电镜 (SEM)结果显示聚亚甲基绿表面呈颗粒状     

含亚甲基链段苯并二(口恶)唑类聚合物的合成、表征及性能

通过溶液缩聚的方法合成了一系列含有不同长度亚甲基链段的聚苯并羟基酰胺(PHACx),然后在200～300 ℃下环化脱水制备了相应的聚多亚甲基苯并二唑(PBOCx),并对其结构进行了表征,探讨了聚合物的溶解性、热性能和光物理性能.研究表明:在主链上引入亚甲基提高了苯并二唑类聚合物在有机溶剂中的溶解性,其中PBOC3 和PBOC4具有较好的溶解性能,但随着亚甲基数量的进一步增加,溶解性有下降趋势.此外,所有的PBOCx聚合物均表现出良好的耐热性,在空气中的热分解温度可达到450 ℃以上.对聚合物光物理性能的初步研究表明:随着柔性链段的增加,电子共轭作用逐渐减弱,紫外吸收发生了蓝移.     

酚醛树脂中亚甲基对热降解的影响

将固化后的酚醛树脂在不同温度下进行热处理,对固化后的样品进行热重分析,对热处理后的试样进行傅立叶红外光谱分析.实验结果表明,酚醛树脂的热降解与亚甲基的取代位有关.酚醛树脂中的亚甲基分两个阶段进行热解降,350~450℃的温度区间主要是部分邻-邻(o-o′)位亚甲基和邻-对(o-p)位亚甲基的分解,400~620℃温度区间为对-对(p-p′)位亚甲基的分解,p-p′位亚甲基比o-o′位亚甲基的起始热分解温度高50℃左右.     

含亚甲基链段苯并二嗯唑类聚合物的合成、表征及性能

通过溶液缩聚的方法合成了一系列含有不同长度亚甲基链段的聚苯并羟基酰胺（PHACx），然后在200～300℃下环化脱水制备了相应的聚多亚甲基苯并二嘿唑（PBOCx），并对其结构进行了表征，探讨了聚合物的溶解性、热性能和光物理性能。研究表明：在主链上引入亚甲基提高了苯并二嘿唑类聚合物在有机溶剂中的溶解性，其中PBOC3和PBOC4具有较好的溶解性能，但随着亚甲基数量的进一步增加，溶解性有下降趋势。此外，所有的PBOCx聚合物均表现出良好的耐热性，在空气中的热分解温度可达到450℃以上。对聚合物光物理性能的初步研究表明：随着柔性链段的增加，电子共轭作用逐渐减弱，紫外吸收发生了蓝移。     

含三氟甲基聚硅烷的合成及其紫外光降解

用Wurtz法合成了聚甲基苯基硅烷、聚(对三氟甲基苯基)(甲基)-甲基苯基硅烷以及聚(对三氟甲基苯基)(苯基)-甲基苯基硅烷3种聚硅烷。用IR、GPC和荧光光谱对产物进行表征,并研究了其紫外光降解性能。从电子结构角度解释了不同聚硅烷在荧光以及紫外光降解行为方面的差异。结果表明,在苯环对位引入吸电子基团三氟甲基有利于紫外光降解的进行,而苯环的增多则会阻碍紫外光降解。     

一种水处理的新方法：金属卟啉和空气存在条件下光催化降解亚甲基蓝水溶液

在４５０Ｗ高压汞灯照射及聚对苯二磺酰氧苯基卟啉钻存在下,考察了亚甲基蓝降解过程中紫外－可见吸收光谱的变化,研究了空气光催化降解亚甲基蓝水溶液反应的动力学。实验结果表明,亚甲基蓝可迅速降解,并且符合一级动力学过程,其现观动力学常数Ｋ＝０．３５４３５ｈ＾－１,半衰期ｔ１／２＝１．９６ｈ,经光催化降解后,亚甲基蓝水溶液脱色率可达５７．４％;其ＣＯＤ浓度降低４３．１％。太阳光具有与高压汞灯相似的作用,这为     

环境化学实验“自制海藻酸钙包覆纳米铁降解亚甲基蓝速率常数的测定”

纳米铁系材料用于去除水体中的污染物是当前环境修复领域的研究热点之一。将自制的海藻酸钙包覆纳米铁材料用于降解亚甲基蓝的实验引入环境化学实验教学中具有极其重要的意义。实验过程包括制备海藻酸钙包覆纳米铁材料,绘制了亚甲基蓝的标准曲线,比较不同材料降解亚甲基蓝的效果,比较不同温度下海藻酸钙包覆纳米铁降解亚甲基蓝的效率,研究温度对其降解速率常数的影响。     

聚对二甲苯纳米纤维阵列的CVD液晶模板法制备及降解性能

聚对二甲苯(PPX)具有优异的生物相容性和化学稳定性, 将其构建成仿细胞外基质结构的可降解纳米纤维在生物工程领域具有重要意义. 本文采用化学气相沉积(CVD)法, 以向列型热致液晶E7为模板, 以4-羟甲基-对二甲苯二聚体(PCP-CH₂OH)为聚-(4-羟甲基-对二甲苯)(PPX-CH₂OH)的前驱体, 通过在其分子链上引入 5,6-苯并-2-亚甲基-1,3-二氧杂环庚烷(BMDO)链段制备BMDO/PPX-CH₂OH共聚物纳米纤维阵列, 探讨了共聚物纳米纤维阵列形貌的影响因素, 分析得到了制备共聚物纳米纤维阵列的最佳反应条件, 并研究了BMDO/PPX-CH₂OH共聚物纳米纤维阵列的生物降解性能. 研究表明, 在液晶模板作用下, 通过CVD法成功地使PCP-CH₂OH与BMDO共聚, 并得到了BMDO/PPX-CH₂OH共聚物纳米纤维阵列; 其形貌主要受样品台的温度和沉积速率的影响, 而单体质量比影响较小; 经优化后CVD最佳条件为: 样品台温度-10 ℃, 沉积速率约为0.01 nm/s, 单体质量比为10∶1; 共聚物在37 ℃的0.1 mol/L Na₂CO₃/0.1 mol/L NaHCO₃的缓冲溶液体系下可有效降解, 当降解时间超过23 d后, 纳米纤维阵列中的酯基可完全分解; 当降解时间超过30 d时, 纳米纤维阵列基本降解完全, 总体呈碎片状.     

TiO2/氧化石墨烯光催化降解亚甲基蓝性能研究

理想的石墨烯具有二维平面结构,其具有良好的机械性能、热导率、高电子迁移率和量子霍尔效应。本文以改进的Hummers法制得氧化石墨烯(Graphene Oxide),超声处理和水热法制备了氧化石墨烯(GO)负载量分别为1.0 wt%、1.5 wt%,2.0 wt%,2.5 wt%的TiO_2/GO复合材料,并通过XRD、TEM等表征手段观察了复合材料的晶相和结构,探讨光催化降解亚甲基蓝性能。结果表明:较之TiO_2,复合材料均具有更大的表面积、更好的亲水性和更强的光催化性能;反应浓度均为2 g·L~(-1)的复合材料,光催化降解10 ppm亚甲基蓝,氧化石墨烯负载量为1.5 wt%的TiO_2/GO复合材料,1 h光催化降解率可达86%,效果最佳。TiO_2/GO复合材料吸附容量大,稳定性良好,能够高效光催化降解偶氮型染料,有望在进一步改良性能后广泛应用于降解工业废水领域。     

Backbone‐Degradable Polymers Prepared by Chemical Vapor Deposition

Polymers prepared by chemical vapor deposition (CVD) polymerization have found broad acceptance in research and industrial applications. However, their intrinsic lack of degradability has limited wider applicability in many areas, such as biomedical devices or regenerative medicine. Herein, we demonstrate, for the first time, a backbone‐degradable polymer directly synthesized via CVD. The CVD co‐polymerization of [2.2]para ‐cyclophanes with cyclic ketene acetals, specifically 5,6‐benzo‐2‐methylene‐1,3‐dioxepane (BMDO), results in well‐defined, hydrolytically degradable polymers, as confirmed by FTIR spectroscopy and ellipsometry. The degradation kinetics are dependent on the ratio of ketene acetals to [2.2]para ‐cyclophanes as well as the hydrophobicity of the films. These coatings address an unmet need in the biomedical polymer field, as they provide access to a wide range of reactive polymer coatings that combine interfacial multifunctionality with degradability.     

Influence of polyfurfuryl alcohol (PFA) loading on the properties of Nafion composite membranes

Composite membranes based on Nafion (N115) loaded with furfuryl alcohol (FA) were prepared by in situ acid-catalyzed polymerization technique, with the aim to improve the ionic conductivity of Nafion membranes. The functionalization, thermal stability, electrical properties and mechanical strength of N115-PFA composites was analyzed by means of Fourier transform infrared (FT-IR) attenuated total reflection (ATR) spectroscopy, small- and wide-angle X-ray scattering (SAXS/WAXS), thermogravimetric analysis (TGA), electrical impedance spectroscopy, dynamic vapor sorption (DVS) and dynamic mechanical analyser (DMA). The FA loading in the resultant composites had a positive correlation with the water uptake (W_u), water vapor uptake (W_vu), ionic conductivity and thermo-mechanical stability. At low polyfurfuryl alcohol (PFA) loading, these membranes displayed higher W_u and improved ionic and electrical properties. Further, the thermo-mechanical stability also gradually increased with the PFA loading. All the composites showed a well-defined glass transition temperature in DMA, which shifted to higher temperature with repeated PFA loading. Overall, the results indicate that the developed composite membrane are promising for low temperature polymer electrolyte membrane (PEM) fuel cells.     

PU/PNIPAM semi-IPN微孔膜温度响应性研究

将聚氨酯(PU)与聚N-异丙基丙烯酰胺(PNIPAM)半互穿网络聚合物(semi-IPN)通过浸入沉淀相转化方法制备成微孔膜,并从亲水性、吸水溶胀性以及透湿性等方面对其温度响应性进行了讨论.PNIPAM的引入使膜的亲水性、吸水性和透湿性大为改善,并显著提高了膜的温度响应能力;但与此同时也使得膜的韧性降低.当PU/PNIPAM为3/1时,可获得最好的综合性能.同传统无孔致密膜相比,PU/PNIPAM semi-IPN微孔膜的透湿机理是基于微孔的开闭,在维持显著的温敏透湿性的同时可实现较高的高温透湿量.     

Properties of poly(<Emphasis Type="Italic">γ</Emphasis>-benzyl <Emphasis Type="SmallCaps">l</Emphasis>-glutamate) membrane modified by polyurethane containing carboxyl group

A series of poly(γ-benzyl l-glutamate) (PBLG)/polyurethane (PU) containing carboxyl group blend membranes was prepared by casting the polymer blend solution in dimethylformamide (DMF). The surface morphology of the PBLG/PU blend membranes was investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Thermal, mechanical, and chemical properties of PBLG/PU blend membranes were studied by differential scanning calorimetry (DSC), tensile tests and other physical methods. It was revealed that the introduction of PU could exert outstanding effects on the morphology and the properties of PBLG membrane.     

Synthesis and characterization of high molecular weight hexafluoroisopropylidene‐containing polybenzimidazole for high‐temperature polymer electrolyte membrane fuel cells

A high molecular weight, thermally and chemical stable hexafluoroisopropylidene containing polybenzimidazole (6F‐PBI) was synthesized from 3,3′‐diaminobenzidine (TAB) and 2,2‐bis(4‐carboxyphenyl) hexafluoropropane (6F‐diacid) using polyphosphoric acid (PPA) as both the polycondensation agent and the polymerization solvent. Investigation of polymerization conditions to achieve high molecular weight polymers was explored via stepwise temperature control, monomer concentration in PPA, and final polymerization temperature. The polymer characterization included inherent viscosity (I.V.) measurement and GPC as a determination of polymer molecular weight, thermal and chemical stability assessment via thermo gravimetric analysis and Fenton test, respectively. The resulting high molecular weight polymer showed excellent thermal and chemical stability. Phosphoric acid doped 6F‐PBI membranes were prepared using the PPA process. The physiochemical properties of phosphoric acid doped membranes were characterized by measuring the phosphoric acid doping level, mechanical properties, and proton conductivity. These membranes showed higher phosphoric acid doping levels and higher proton conductivities than the membranes prepared by the conventional membrane fabrication processes. These membranes had sufficient mechanical properties to be easily fabricated into membrane electrode assemblies (MEA) and the prepared MEAs were tested in single cell fuel cells under various conditions, with a focus on the high temperature performance and fuel impurity tolerance. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4064–4073, 2009     

Tailoring Morphology of PVDF-HFP Membrane via One-step Reactive Vapor Induced Phase Separation for Efficient Oil-Water Separation

Poly(vinylidene fluoride-co-hexafluoropropylene)(PVDF-HFP) receives increasing attention in membrane separation field based on its advantages such as high mechanical strength, thermal and chemical stability. However, controlling the microporous structure is still challenging.In this work, we attempted to tailor the morphology of PVDF-HFP membrane via a one-step reactive vapor induced phase separation method.Namely, PVDF-HFP was dissolved in a volatile solvent and then was cast in an ammonia water vapor atmosphere. After complete evaporation of solvent, membranes with adjustable porous structure were prepared, and the microstructures of the membranes were analyzed by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy and X-ray diffraction characterizations. Based on the results, a mechanism of dehydrofluorination induced cross-linking of PVDF-HFP has been suggested to understand the morphology tailoring.To our knowledge, this is the first report of one-step reactive vapor induced phase separation strategy to tailor morphology of PVDF-HFP membrane. In addition, the membranes prepared in the ammonia water vapor exhibited enhanced mechanical strength and achieved satisfactory separation efficiency for water-in-oil emulsions, suggesting promising potential.     

Poly(silmethylene)-based polymer blends. I. In situ polymerization of 1,3-disilacyclobutanes in silicon-based polymers

The in situ polymerization of 1,1,3,3-tetraphenyl-1,3-disilacyclobutane with or without a catalyst in flexible organo-silicon polymers was demonstrated to provide poly(silmethylene)-based polymer blends. An alternative route, which implies preparation of blends via synthesis of a flexible polymer in the presence of a rigid polymer, was also promising. The resulting polymer blends were characterized by DSC, dynamic mechanical analysis, and solvent extraction. No chemical interaction is observed between component polymers of blends prepared by the in situ bulk polymerization method while formation of block or graft copolymers comprising poly(diphenylsilmethylene) and flexible polymers is suggested when in situ copper-catalyzed polymerization was employed. A morphological difference between samples synthesized by the different methods was suggested by microscopic observation. © 1997 John Wiley & Sons, Inc.     

The effect of production method on the properties of high impact polystyrene and polyaniline membranes

In this study, different membranes were prepared using conventional polymer (high impact polystyrene) and polyaniline to evaluate their use in electrodialysis. Two different preparation modes were tested: chemical mixture with subsequent solvent evaporation; and mechanical mixture with subsequent pressing under heating. The purpose was to understand the effect of production methods on membrane microstructure and ionic transport. Membranes were characterized by swelling study, Fourier transformed infrared spectroscopic, scanning electron microscopy, thermogravimetric analysis and dynamic mechanical analysis. Ionic transport through the membranes was evaluated using a three-compartment cell. The results of the produced membranes were compared with those of the commercial Nafion 450 membrane.