高透明度聚乙烯醇水凝胶的制备、表征及透明机理研究

Preparation,characterization and transparence mechanism analysis of high-transparent poly(vinyl alcohol) hydrogels

用二甲基亚砜(DMSO)水溶液通过冷冻/解冻法制备了高透明度聚乙烯醇(PVA)水凝胶,使用差示扫描量热仪(DSC)、紫外吸收光谱、力学性能分析仪、紫外-可见分光光度计等分析了DMSO浓度对聚乙烯醇水凝胶透光率的影响,并表征了PVA水凝胶的含水率、结晶度、力学性能等性质。结果表明,用含量为80%(质量分数)的DMSO水溶液制备的PVA水凝胶得到了高达(99.8±0.2)%透明度,其抗拉强度达到3MPa以上,断裂拉伸率>600%。研究发现,DM-SO与水形成的1DMSO/2H2O网络结构能够限制PVA分子在三维方向的结晶,同时能够促进二维方向PVA晶体的生长。当DMSO含量为80%时,溶液中DMSO与水的比例略>1∶2,存在少量未形成1∶2网络结构的DMSO分子,该分子与PVA羟基形成氢键限制了PVA分子在二维方向的结晶,最终导致PVA水凝胶中PVA晶体的体积最小、PVA晶体的数目最多,从而得到了最高的水凝胶透明度和较好的力学性能。

In this paper,transparent poly（vinyl alcohol）（PVA） hydrogels were prepared by using the solvent of Dimethyl-sulfoxide（DMSO） aqueous solution and the method of freeze/thawing. The effect of DMSO/H2O interaction on the crystallinity,mechanical property and transparence of PVA hydrogel was investigated and evaluated by using DSC, UV spectra,mechanical properties test machine and UV-vis spectrophotometer. Moreover an interaction model of 1DMSO/2HzO mixture was provided and discussed. The results show that when the DMSO content was 80% in the DMSO aqueous solution,the highest transparence of PVA hydrogel was obtained ,with the tensile strength values higher than 3MPa,and the elongation ratios at break about 600%. According to our investigation,it is found that the size of PVA crystal in PVA hydrogel reduced, the PVA crystal amount increased,and the transparence and mechanical properties of PVA hydrogel enhanced due to the strong intermolecular action and the network formation in 1DMSO/2H2O mixture. Furthermore,the mechanism enhanced optical property of PVA hydrogel was provided in this paper.