Energy of Salt Formation and Supramolecular Ordering of Chitosan L- and D-Ascorbates

Using two samples of chitosan (D-glucan) with viscosity-average molecular mass 40 × 103 and 200 × 103 as the example, the influence of diastereomer form (L- and D-) of ascorbic acid on the energetics of formation, structure, and supramolecular ordering of hetero- (D‒L) and homochiral (D‒D) polymer–acid salt complexes has been studied. It has been found that heat effect during the interaction of chitosan with L-ascorbic acid in aqueous medium and degree of protonation of the (D‒L)-salts are lower in comparison with D-isomer of the acid. The homochiral (D‒D)-salts, in contrast to the heterochiral (D‒L)-salts, have exhibited lower amount of crystallization water, high degree of crystallinity, and denser supramolecular structure with high level of inter- and intramolecular contacts.