K-型卡拉胶/聚乙烯吡咯烷酮共混水凝胶的辐射合成

采用辐射技术合成了K 型卡拉胶 (KC) /聚乙烯吡咯烷酮 (PVP)共混水凝胶 ,研究了天然高分子KC、单体N 乙烯基吡咯烷酮 (N VP)、交联剂二甲基丙烯酸十四甘醇酯 ( 1 4G) ,辐照剂量以及剂量率等对辐射合成的KC/PVP共混水凝胶性质的影响 .实验发现 ,KC与适当比例的N VP共混后在一定剂量范围内辐照可得到高强度、高溶胀行为的KC/PVP共混水凝胶 ,随着共混凝胶内KC含量的相对增加 ,凝胶强度及溶胀性的能均显著提高 ,但合成该共混凝胶的最佳剂量却相对提前 ;加入 1 4G后降低了KC/PVP共混凝胶辐射合成最佳剂量 ,同时使KC/PVP共混凝胶的强度进一步提高 ;剂量、剂量率对KC/PVP共混凝胶的性质亦有很大的影响 .分析表明 ,KC与N VP共混后 ,在较低剂量下KC的降解被抑制 ,从而获得一种由物理交联的KC和化学交联的PVP形成的互穿网络 (IPN)凝胶     

有耗介质探地雷达波传播衰减特性的研究

探地雷达是利用超高频脉冲电磁波探测地下介质分布的一种浅层地球物理勘探方法,探地雷达超高频、宽频带脉冲电磁波在地下有耗介质中的衰减特性是一个十分复杂的过程。本文从电磁波传播的麦克斯韦方程出发,较为系统地研究和分析了雷达脉冲电磁波在有耗介质中传播的衰减特性,对研究雷达脉冲电磁波在地下有耗介质中的传播机制有指导意义。     

κ-型卡拉胶/聚乙烯吡咯烷酮共混水凝胶的辐射制备及性质研究

采用辐射技术制备了κ-型卡拉胶 ( KC) /聚乙烯基吡咯烷酮 ( PVP)共混水凝胶 ,研究了共混凝胶内 KC含量、PVP的分子量和辐照剂量等对 KC/ PVP共混水凝胶性质的影响 .实验发现 ,KC与高分子量的 PVP( k-90 )共混后在一定剂量范围内辐照可得到高强度、高溶胀行为的 KC/ PVP共混水凝胶 ,随着共混凝胶内KC含量的增加 ,凝胶强度及溶胀性能均显著提高 .分析表明 ,KC与高分子量的 PVP共混后 ,在较低剂量下 KC的降解被抑制 ,从而获得一种由物理交联的 KC和化学交联的 PVP形成的互穿网络 ( IPN)凝胶 .     

钒(V)化合物在硫酸中的电化学行为研究

应用循环伏安法和旋转环盘电极法研究了H2 SO4 溶液中五价钒化合物 (NH4 VO3和V2 O5)的电化学行为 .由光滑Pt电极测得其CV图 ,两者的基本峰位和峰形都很相似 ,通常出现三个还原峰和三个氧化峰 ,但NH4 VO3多一个氧化峰 ,RRDE测定也出现了四个氧化峰 ,本文分析了这些对应峰的反应 ,并给予初步解释     

溶胀动力学法测定高聚物溶度参数

用溶胀性能测定仪，以溶胀动力学方法成功地测定了线型及交联高聚物的溶度参数，此方法较传统的特性粘数极大值法及平衡溶胀度方便、省时、省力、易于推广。     

New superporous hydrogels composites based on aqueous Carbopol solution (SPHCcs): synthesis, characterization and in vitro bioadhesive force studies

In this investigation new superporous hydrogels composites based on aqueous Carbopol^® solution (SPHCcs) were prepared. SEM images indicated that the inner surface of SPHCcs contained a lot of pores connected each other and the outer surface of them was non-porous. The swelling ratio decreased with increasing the content of aqueous Carbopol^® solution, and the final swelling ratio was similar to that of the SPH although the initial swelling ratio was lower. The density measurement revealed that the porosity increased when aqueous Carbopol^® solution was incorporated. It was observed from in vitro bioadhesive force study that SPHCcs adhered to the intestinal mucosal more quickly and exhibited higher mucoadhesion as compared with SPH. It is evident that the hydrogels synthesized in this study could be a potential candidate for transmucosal drug delivery system.     

Solid-State Polymerization of N-Vinylcarbazole by Redox Catalyst

A crystal of N-vinylcarbazole was polymerized by redox catalyst (ammonium persulfite/sodium bisulfate) in a suspended state in water and poly (vinyl carbazole) was obtained. The polymerization proceeded rapidly above 40°C without an induction period in the solid state. The molecular weight of the polymer increased with decreasing catalyst concentration and raising temperature. ηsp/^c of polymer was in the range 0.04–0.07 and it was lower than that obtained in radiation-induced solid-state polymerization. Observation of the partially polymerized crystal through a polarizing microscope showed that the polymerization proceeded from the surface of the monomer crystal and that birefringence was observed in the polymer layer. In X-ray diffraction studies it was found that the polymer was crystalline.     

Modeling Investigation of Volume Variation Kinetics of Fast Response Hydrogels

Abstract

Fast response hydrogels have attracted great attention recently. Three kinds of models with different complexity are available in the literature to investigate their volume variation kinetics. A phenomenal model based on second‐order reaction kinetics provides a simple method to correlate the experimental kinetic data. A power law model can be employed to evaluate different volume variation mechanisms according to the diffusion exponential coefficient. The multi‐field model incorporates mechanical deformation with the diffusion of ion species. The volume variation rate is dependent on both hydrogel molecular design and operation conditions.     

On the swelling behavior of linear end-grafted polystyrene in methanol/toluene mixtures

Neutron reflectivity measurements have been performed with polystyrene (PS) brushes of different graft densities ranging from =0.020 to =0.051 in contact with toluene/methanol mixtures of different composition. The brushes were prepared by a grafting-from procedure resulting in linear chains of average molecular weight _n=300,000 g mol^–1. The recorded reflectivity curves could be analyzed to a first approximation by assuming a flat scattering length density profile within the brush normal to the surface with a moderate Gaussian smearing of the interface brush/solvent. With increasing toluene content a substantial thickness increase was found with the swollen brush at 70 vol.% being 3.7 times thicker than the dry collapsed film. At low toluene contents the preferential incorporation of this good solvent for the PS brush exceeds a factor 3.5 relative to the molar ratio of the bulk solvent mixture with methanol.

高分子间相互作用的特点及意义

高分子间的相互作用与小分子间的相互作用有着显著的区别，导致高分子物质在凝聚态结构和诸多性能上明显地有别于小分子物质。本文就如下七个方面：特别强的高分子间相互作用、特殊的高聚物溶解过程、马克三角形原理、特征温度、特有的单链凝聚态、凝聚缠结和超分子体系来讨论高分子间相互作用的重要性及其对高聚物的结构和性能的影响。