Selective transport of cesium ion in polymeric CTA membrane containing calixcrown ethers

A series of calixcrown ethers for which the cavity size of the crown ring is varied from crown-6 to crown-7 to crown-8 were examined for the transport abilities toward alkali metal ions. These ligands were incorporated into supported liquid membranes (SLMs) and into polymer inclusion membranes (PIMs) composed of cellulose triacetate (CTA) as a support and 2-nitrophenyl octyl ether (NPOE) and tris(2-butoxyethyl) phosphate (TBEP) as a plasticizer. In both membrane systems, calixcrown-6 showed the best selectivity toward a cesium ion over other alkali metal ions. The polymeric CTA membrane showed more rapid transport rate as well as higher durability than did the SLMs.     

Protective Properties of Zinc-Rich Coatings: An Impedance Method Estimate

The impedance of zinc-rich polymer coatings on steel in a 3-% NaCl solution is studied. The electrochemical behavior of the electrode is satisfactorily described by an equivalent circuit that contains a constant-phase element, which reflects fractal properties of the zinc surface in the binder. From the results of calculations of the circuit elements for metal-rich electrodes with different zinc contents computed are fractions of the active area of the surface of the coating and its fractal dimensionality.     

Hydrogels in aqueous phases of polyvinylalcohol (PVA), surfactants and clay minerals

Aqueous solutions of synthetic clay minerals have been studied in the presence of surfactants and water-soluble polyvinylalcohol (PVA). The PVAs (PVA 1, PVA 2) had a molecular weight of about 10⁵ Dalton and a degree of hydrolysis of 82%. The PVA-samples were surface active and lowered the surface tension to 43 mN/m. As a consequence of their amphiphilic nature the PVA molecules bind strongly to clay mineral particles. On saturation the clay mineral particles adsorb the fivefold weight of PVA of their own weight. It is concluded that the thickness of the adsorbed layers on both sides of the clay mineral is in the range of the hydrodynamic diameter of the PVA-coils in the bulk phase.When the clay mineral particles are not saturated with PVA, they act as cross-linking agents for the PVA. The whole systems are physically cross-linked and assume gel-like properties. Rheological measurements show that samples behave like soft matter with a yield stress value. All of them have a frequency independent storage modulus which is an order of magnitude larger than the loss modulus. The hydrogels become stronger as PVA concentration increases.Small amounts of cationic surfactants bind on the clay mineral. The interface of the clay mineral becomes more hydrophobic and the binding of the PVA on the clay mineral is strengthened. With rising concentration of the surfactant the surfactant molecules bind on PVA and the PVA becomes hydrophilic. As a consequence the PVA can no longer bind on the clay mineral and the gels transform to viscous and turbid solutions. Small amounts of cationic surfactants therefore stiffen the hydrogels while larger amounts cause phase separation and a solution with low viscosity. Anionic surfactants like SDS do not bind on the clay mineral, but strongly on the PVA. With increasing SDS concentration, the hydrogels become stiffer at first but thereafter they break and transform to viscous fluids.In PVA-solutions without the clay minerals both cationic and anionic surfactants bind to the PVAs in the aqueous solution. With increasing concentration of surfactant, the viscosities of the solutions pass over a maximum. In this respect the PVAs behave like hydrophobically modified water soluble polymers. The surfactants bind to the hydrophobic microdomain and thereby crosslink the polymer molecules. On saturation the polyvinyl alcohol with anionic surfactant become hydrophilic and the network character disappears to a certain extent.     

CZE separations of basic proteins at low pH in fused silica capillaries with surfaces modified by silane derivatization and/or adsorption of polar polymers

Mixtures of several basic proteins have been used to test CZE capillaries with surfaces modified by new pretreatment procedures; the performance obtained has been compared with that achieved using capillaries treated by procedures described in the literature. It has been shown that addition of non-ionic polyvinylalcohols (PVA) to CZE buffer solutions deactivates even bare, i.e. untreated, fused silica surfaces and renders them suitable for separations of basic proteins. The performance obtained from such surfaces was comparable with that of capillaries modified by the more elaborate procedures of etching, silanol derivatization, and/or adsorptive coating (again with polymers). A home-made device is described which enables derivatization and coating reactions to be performed on fused silica capillaries under an inert atmosphere, i.e. one free from oxygen and water.     

聚酰亚胺／聚N－乙烯吡咯烷酮分子复合物的合成和表征

由原位缩聚制备了刚性高分子聚酰亚胺（ＰＩ）和柔性基体聚Ｎ－乙烯吡咯烷附（ＰＶＰ）的分子复合物，并由实验证明了中间体聚酰胺酸（ＰＡ）和聚乙烯吡咯烷酮大分子之间存在的酸一碱相互作用．这种相互作用促进了混容性，使聚酰亚胺能以分子水平或接近分子水平分散在聚毗咯烷酮的基体之中．聚酰亚胺／聚Ｎ－乙烯吡咯烷团分子复合物的薄膜呈透明性，在整个组成范围内只有一个Ｔｇ，显示单相行为。当ＰＩ含量＜２０％时，ＳＥＭ相片呈现均相形貌，看不到ＰＩ微晶．广角Ｘ－ｒａｙ衍射图表明ＰＩ特征结晶峰消失，和无定形的ＰＶＰ完全混容．当ＰＩ含量＞４０％，ＳＥＭ显示有均匀分布的、棒状ＰＩ微晶存在．通过分子复合，即使ＰＩ含量为１０％，聚Ｎ－乙烯吡咯烷酮不再溶于乙醇，耐热性也有提高．     

《高分子化学》课程中“活性自由基聚合”的教学实践

《高分子化学》课程是五大化学基础课程(无机化学、有机化学、分析化学、物理化学、高分子化学)之一,是化学类、高分子材料与工程、材料化学专业的必修课程。"活性"/可控自由基聚合是一种相对较新且重要的聚合物合成技术和方法,针对目前《高分子化学》课程中活性自由基聚合的教学比较薄弱的现状,从教学的角度探讨了活性聚合和可控/"活性"自由基聚合的本质和特点,介绍了本人在这方面的教学实践活动,遵循成果导向教育理念,通过以学为中心的教学方式,打造金课,提高教学质量。     

ITSTUDIES ON THE EFFECT OF UREA ON THE COMPATIBILITY OF PMMA/PVC MIXTURES IN DMF BY A DILUTE- SOLUTION VISCOMETRY METHOD

The interaction between poly(methymethacrylate) (PMMA) and poly(vinyl chloride) (PVC) has been studied indilute urea solutions of dimethylformamide (DMF) at 28℃ using a dilute solution viscometry method. The results show thatthe polymer mixtures are compatible in DMF solution in the absence of urea. The influence of urea addition on the degree ofcompatibility of the polymer mixtures has been studied in terms of the compatibility parameters (△b_m and △[η]_m). It wasfound that the compatibility of the polymer mixtures is decreased with increasing urea addition, passing through a minimumat 0.5 M urea.     

热致液晶共聚酯对聚丙烯结晶的诱导作用

用差示扫描量热法和光学解偏振法研究了热致液晶性芳香共聚酯与聚丙烯共混物的等温和非多温结晶行为.结果表明,这一热致液晶聚合物对聚丙烯结晶有诱导成核和加速作用.当共聚酯含量在2-5％之间时,聚丙烯的结晶速率最快.偏光显微镜的观察揭示出在聚丙烯熔体中原位形成的液晶聚合物微纤诱导了聚丙烯横穿晶的形成.     

环氧丙烯酸酯的紫外光固化

制备了适于配制紫外光固化涂料的环氧丙烯酸酯，研究了反应温度、阻聚剂、催化剂等因素对环氧树脂与丙烯酸反应的影响；讨论了反应机理和动力学；并利用红外光谱观察了产物的紫外光固化行为。季铵盐能有效地催化环氧树脂和丙烯酸的反应，当其用量为０．６％～１．２％时，在９０～１１０℃反应４．５～８小时后，环氧基转化率大于９７％。由此配制的光固化涂料经紫外光辐照能快速固化。     

聚合物共混物脆韧转变性能研究 Ⅱ准韧性聚合物共混物脆韧转变的几何模型

给出了分散相粒间基体层厚度Ｔ与分散相粒径（ｄ）、粒径分散度（σ）和分散相体积分数（）的定量关系式．发现σ对Ｔ的影响与有关，不仅Ｔ随σ的增大而增大，而且越大，这种影响越显著．用计算机图像分析仪直接测定了聚氯乙烯／丁腈橡胶、聚丙烯（ＰＰ）／三元乙丙橡胶、ＰＰ／乙烯 醋酸乙烯酯共聚物共混物的Ｔ，发现这三种共混物的Ｔ近似于对数正态分布．理论预示与实验结果很好符合．