Thermodynamic study of functionally modified chitosan and its blends in aqueous media at 298.15Â K

Linear polysaccharides, negatively charged N-methylene phosphonic chitosan (NMPC) and positively charged quaternized chitosan (QC) were synthesized. Thermodynamic study of the synthesized materials NMPC, QC and the mixture of equal concentrations of NMPC + QC was carried out in aqueous media at 298.15 K. Solute-solvent interactions have been studied through ultrasonic, viscometry and densitometric techniques. Isentropic compressibilities of the polymer solutions and hydration number of monomeric units in the functionalized chitosan and their blends or different systems were derived using experimental values of speed of sound and densities. Viscometric studies were used in estimating average molecular weight Mv of polymers and their blends and solute-solvent interaction parameter χ for quantitative estimation of solute-solvent interactions.