Polybiguanides: Synthesis and characterization of polybiguanides containing hexamethylene groups

A series of polymeric biguanide hydrochlorides containing hexamethylene groups has been synthesized by developing methods for melt and solution polymerization, based on the reaction of cyano groups with amine hydrochlorides. These polymers were characterized by solution viscometry, gel permeation chromatography, H-1 n.m.r. and i.r. spectroscopy and thermal analyses (d.s.c. and t.g.a.). The presence of some melamine groups in the polymers made by melt polymerization was noticed and identified based on i.r. spectroscopy. The polymer salts obtained were generally hygroscopic and water soluble and lacked crystallinity. The hygroscopicity of the polymers varied with the hydrocarbon groups contained in the chains and the extent and nature of salt formation. The polybiguanide salts in both aqueous and polar nonaqueous solutions showed typical solution viscosity features of polyelectrolytes. The polybiguanides readily formed coloured complexes with copper ions. (C) 1997 Elsevier Science Ltd.