Effect of acetylation on physico-chemical properties of bacterial and algal alginates in physiological sodium chloride solutions investigated with light scattering techniques

Static light scattering measurements were performed to investigate the effect of acetylation on the physico-chemical properties of alginates in salt solutions from different sources. Although chemical acetylation reduces the molar mass of algal alginate by 27%, it has a size increasing effect on the alginate clusters. The influence of molar mass on the dimensions of polymer aggregates is outweighed by the effect of acetyl groups. Negative virial coefficients are found which become more positive for acetylated alginates. They give another explanation of the size increasing effect of acetylation on the cluster size since acetylated alginates show a better interaction mainly with the water molecules of the salty solution than unacetylated alginates do.