McNeill M E, Graham N B
Department of Pure and Applied Chemistry, University of Strathclyde, Glasgow, UK.
J Biomater Sci Polym Ed. 1993;4(3):305-22. doi: 10.1163/156856293x00582.
This study examines the state of water-association with poly(ethylene oxide), as evidenced by diffusivity, in a series of crosslinked polyurethanes made from poly(ethylene glycols) of a range of molecular weights. As a subsidiary underpinning exercise the correlation of diffusivity with water content at relatively high levels of swelling (> 45%) using a variety of semi-empirical equations was analyzed. Three water-soluble compounds with similar molecular weights and which exhibit minimal interaction with the polymer, as shown by their partition coefficients, were chosen for this part of the research programme. These were proxyphylline, morphine hydrochloride and caffeine. The best statistical correlations of the data were obtained for plots of: (a) diffusivity against weight percent water; and (b) log diffusivity against the reciprocal of the weight percent of water in the hydrogels. Proxyphylline results for the high levels of swelling compositions were augmented with data from lower swelling compositions and a clear break in the slope of diffusivity against percentage of water in the swollen hydrogel was obtained. This indicated a change in the nature of the diffusion at this point. The probability of this transition point corresponding to a change for diffusion through water bound as trihydrate to diffusion in free water is discussed.
本研究考察了一系列由不同分子量聚乙二醇制成的交联聚氨酯中，水与聚环氧乙烷缔合的状态，这可通过扩散率来证明。作为一项辅助性基础工作，分析了使用各种半经验方程，在相对较高溶胀水平（> 45%）下扩散率与含水量的相关性。本研究项目的这一部分选择了三种分子量相似且如分配系数所示与聚合物相互作用极小的水溶性化合物。它们是丙羟茶碱、盐酸吗啡和咖啡因。对于以下两种情况的数据图，得到了最佳统计相关性：（a）扩散率对水的重量百分比；（b）对数扩散率对水凝胶中水的重量百分比的倒数。高溶胀组合物的丙羟茶碱结果用低溶胀组合物的数据进行补充，得到了扩散率对溶胀水凝胶中水百分比的斜率的明显突变。这表明此时扩散性质发生了变化。讨论了该转变点对应于从通过三水合物结合水的扩散转变为在自由水中扩散的可能性。
