PVP在水/四氢呋喃混合溶剂中粘度的研究

Studies on Viscosity of PVP in Mixed Solvents H_2O/THF

采用高分子稀溶液粘度法研究了聚乙烯基吡咯烷酮 (PVP)在水 (H2 O)和四氢呋喃 (THF)组成的混合溶剂中的粘度行为 ,结果表明 ,PVP在由良溶剂H2 O和非溶剂THF组成的混合溶剂中的特性粘数可以大于其在良溶剂H2 O中的特性粘数 ,并且随着THF含量的增加呈现先增大后减小的变化趋势 ,特性粘数的最大值出现在THF的体积分数约为 0 .3处 ,而且无机盐Na2 SO4 的加入没有改变特性粘数的最大值位置 ,但减小了特性粘数值 .基于分子的基本特征和分子间的相互作用 ,特别是考虑到混合溶剂中新的结构———包合结构的形成及其对溶剂性能的影响 ,讨论了PVP的特性粘数和链尺寸的相应变化 。

The dilute solution viscometer is used to research the ternary solution of Poly(N vinylpyrrolidone)(PVP) in mixed solvents H 2O/THF. H 2O is the good solvent of PVP, and THF the non solvent. The viscometric study indicates that the intrinsic viscosity η of PVP may be higher in the mixed solvents than in the pure solvent H 2O and change with the variation of the volume fraction of THF, . It is found that at first η increases slowly and then decreases rapidly with the adding of THF. A maximum value of η appears at ≈0.3, which decreases after the adding of Na 2SO 4, but the value of , at which the maximum value of η appears, varies relatively little. The change in values of η and coil dimensions in mixed solvents are discussed in terms of the molecular characteristics of the system and intermolecular interactions, especially in terms of the form of new structure—clathrate hydrate structure, and the relative influence upon the nature of solvent. It is stated that the properties of ternary systems (polymer/mixed solvent) might not be deduced directly from those of the binary systems composed of each component liquid.