Primary study on the assay of superficial hydroxyl group content upon the solid polyvinyl alcohol

Polyvinyl alcohol is a multipurpose polymer, and there is abundant hydroxyl group on its surface. In this article, we first time attempted to assay the superficial hydroxyl group content on the solid polyvinyl alcohol (PVA–1799) with a degree of polymerization over 1700 and a degree of alcoholysis over 99.0%. The assay was carried out by two different titration systems. The results show: (1) the order of magnitude of superficial hydroxyl group content on its solid surface was about 3.8E-5 mol/cm2 by acylation system with single functional group reagent (acetic anhydride); while (2) the order of magnitude of superficial hydroxyl group content was about 1.4E-7 mol/cm2 by esterification system with bi-functional group reagent (Toluence 2,4-DiIsocyanate, TDI). The results would be useful to provide a quantitative reference when –OH on the solid PVA surface is intended to be utilized for surface modification for some application. Moreover, the results and their difference also offer us the knowledge of the surface modification efficiency.