Department of Chemistry, The Pennsylvania State University, University Park, Pennsylvania 16802, USA.
J Phys Chem B. 2011 Mar 31;115(12):2759-64. doi: 10.1021/jp109451d. Epub 2011 Mar 8.
Electric conductivity measurements indicated that microviscosities of poly(vinyl alcohol), PVA, solutions [up to 10% (w/w)] are comparable to that of pure water (contrary to Walden's rule), but are different (25%) from those determined from diffusion-controlled reaction measurements that coincide with the values obtained using pure water. Energies of activation of fluidity of PVA solutions are found to increase with PVA concentration, whereas those of the diffusion-controlled reactions are independent of PVA concentration. By comparing the macro- and microviscosities, it was concluded that PVA aqueous solutions can be envisioned as dynamic systems comprising hydrated PVA molecules (that affect the macroviscosity) and "interconnected water pools" (located between macromolecules), the rheological properties of which are very similar to that of pure water. Fluorescence depolarization measurements indicated that pool sizes are relatively large, which was corroborated by DSC measurements that showed that each PVA hydroxyl group interacts with no more than two water molecules.
电导率测量表明，聚乙烯醇（PVA）溶液的微粘度[高达 10%（w/w）]与纯水相当（与 Walden 规则相反），但与扩散控制反应测量所确定的粘度不同（相差 25%），后者与使用纯水获得的值一致。发现 PVA 溶液的流动性活化能随 PVA 浓度的增加而增加，而扩散控制反应的活化能则与 PVA 浓度无关。通过比较宏观和微观粘度，可以得出结论，PVA 水溶液可以被设想为包含水合 PVA 分子（影响宏观粘度）和“相互连接的水池”（位于大分子之间）的动态系统，其流变性质与纯水非常相似。荧光各向异性测量表明池的尺寸相对较大，这一点得到差示扫描量热法（DSC）测量的证实，该测量表明每个 PVA 羟基与不超过两个水分子相互作用。
