Fluorocarbon-modified water-soluble cellulose derivatives

Abstract

1,1-Dihydroperfluorobutyl,1,1-dihydroperfluorooctyl, and octyl derivatives of (hydroxyethyl)-cellulose (HEC) were prepared by reaction of the Na salt of HEC in aqueous isopropyl alcohol with 1,1-dihydroperfluorobutyl or octyl p-toluenesulfonate (4 or 5), with 1,1-dihydroperfluorobutyl or octyl glycidyl ether or (8 or 9), and with octyl glycidyl ether (12). The degrees of substitution of HEC were determined using [sup 19]FNMR and varied between 0.023 and 1.20 mol % of anhydroglucose units (AGU). The HEC derivatives modified with 4, 5, and 8 were sparingly soluble or insoluble, and their aqueous solutions were generally low in viscosity. In contrast solutions of HEC modified with 9 did have significantly enhanced viscosities with respect to unmodified HEC or compared to HEC modified with the octyl glycidyl ether, having the same chain length as 9. The Brookfield viscosity plotted against perfluorocarbon content of aqueous solutions of HEC modified with 9 was shown to go through a maximum at about 0.42 mol % (0.92 wt %) with respect to AGU's. The solutions of this and similar polymers were shown to be highly pseudoplastic. Furthermore, increases in viscosity were observed upon addition to NaCl. These observations are consistent with the very strong intermolecular hydrophobic association of the perfluorocarbon groups.