Solution and gelling properties of polysaccharide polyelectrolytes.

Attention is focussed on the special class of polysaccharide polyelectrolytes belonging to the family of the microbial polysaccharides. But a few exceptions, these are high molecular weight water- soluble polycarboxylates with complex, regular structures. Complexity and regularity in primary structure--two features normally not shared by other polysaccharides of either vegetal or animal origin--quite naturally entail unique conformational propensities, special physico-chemical properties in bulk and in solution and, as a consequence, make these biopolymers of particular interest from both a basic research and an industrial standpoint. What is outlined in this presentation should demonstrate that for many exocellular microbial polycarboxylates the solution properties are, as expected, dictated by the conformation assumed by the polyelectrolytic chains which, in turn, are governed by several free energy terms in particular stemming from specific solvent-chain interactions, among which the coulombic contribution may play a minor role.