Preparation and characterization of chitosan amino acid salts

Chitosan has many unique properties, such as the extensive sources, renewability, excellent biocompatibility and biodegradability. To improve the water solubility of chitosan is an effective approach to overcome the limitations of its application. In this paper, three water soluble chitosan acid salts were prepared via a simple and green process by using chitosan and amino acids as the original materials. The water solubility and the moisture absorption of the prepared chitosan salts were tested. Meanwhile, three chitosan amino acid salts were characterized by Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction (XRD) and potentiometric titration. The results showed that the water solubility of three chitosan salts was greatly improved and the moisture absorption was more than 15.3%-32.8% higher than that of chitosan. Structural analysis indicated that the formation of chitosan amino acid salts were via protonation reaction rather than simple physical adsorption. Relative to chitosan, the crystallinity of chitosan amino acid salts were decreased. The structural change of chitosan has greatly improved its performance and expanded its application fields.