Novel Nonionic Oligosaccharide Surfactant Polymers Derived from Poly(vinylamine) with Pendant Dextran and Hexanoyl Groups

Abstract

A series of novel surfactant polymers: poly(N-vinyldextran aldonamide-co-N-vinylhexanamide) (PNVDA-co-PNVH), in which hydrophilic dextran oligosaccharides and hydrophobic hexanoyl groups were incorporated simultaneously on to poly(vinylamine) (PVAm), were synthesized, and characterized by FTIR and 1H NMR spectroscopy. Structurally well-defined poly(vinylamine) was prepared by hydrolysis of poly(N-vinylformamide), which was obtained by free radical polymerization of N-vinylformamide. Dextran molecules (Mw = 1600) were attached to poly(vinylamine) by reacting amine groups with dextran lactone, while hexanoyl groups were attached by reacting amine groups with N-(hexanoyloxy)succinimide. By adjustment of the feed ratio, surfactant polymers with different hydrophilic/hydrophobic balances were prepared. Surface activity of the surfactants at an air/water interface was demonstrated by significant reductions in water surface tension. Surface activity at a solid surface/water interface was demonstrated by atomic force microscopy of surfactant molecules adsorbed onto a highly oriented pyrolytic graphite. The synthetic approach described in this report provides a route to prepare a variety of oligosaccharide surfactant polymers with well-defined structures and hydrophilic/hydrophobic balances, by selecting different combinations of oligosaccharide and alkanoyl groups or by adjusting feed ratio of the oligosaccharide to alkanoyl groups.