Influence of chain stiffness on the gelation and gel structure of alginate aqueous systems

The influence of chain stiffness on critical gel concentration and gel structure has been studied with rheological and small-angle X-ray scattering SAXS) measurements using aqueous systems of alginates having different mannuronate/guluronate (M/G) ratios. Gelation occurs at a polymer concentration where the number of intermolecular interaction points (IIPs) per polymer molecule reaches a certain critical value which is independent of the molecular weight. The number of IIPs at the gel point is smaller in the stiff chain systems than in the more flexible chain systems. The fractal dimension of the gel at the gel point is larger in the stiff chain systems than in the more flexible chain systems.