Synthesis and liquid-crystalline behaviour of liposaccharide based comb polymers

Abstract

In order to investigate the relationship between the liquid-crystalline state and the biological properties of polymers, we synthesized and studied liquid-crystalline comb polymers with a polyacrylamide main chain and three types of lipo-saccharidic side chains. These comb polymers were synthesized in four steps: first the polymerizable group was linked to the amino end of an α,ω-aliphatic amino acid; in the second step the ω-carboxylic acid function was activated in the form of an N-hydroxysuccinimidylester; in the third step the active ester was aminolysed by the amine function of the saccharide (N-methyl-D-glucamine, 2-amino-2-deoxy-β-D-glucose or 1-amino-1-deoxy-β-D-galactose) and a polymerizable liposaccharide was obtained; finally the liposaccharides were transformed into comb polymers by free-radical polymerization. Comb polymers exhibit mesophases in concentrated aqueous, ethanol or dimethylsulphoxide solution, and their mesomorphic character remains after the slow evaporation of the solvent. X-ray diffraction studies have shown that the mesophases have smectic or nematic ordering, depending upon the nature of the saccharidic residues of the liposaccharidic side chains.