Preparation and characterization of chitosan, CM-chitin and CM-chitosan scaffolds by using freeze-drying technique

Porous scaffolds of chitosan, carboxymethylchitin (CM-chitin), and carboxymethylchitosan (CM-chitosan) were fabricated via freeze-drying technique and further crosslinked by steam treatment in an autoclave. The effect of steaming temperatures on crosslinking of the polymers was investigated. The degrees of swelling, mechanical properties, and morphology of the steamed scaffolds were evaluated. The changes in chemical structures of the scaffolds after steam treatment were observed by FT-IR spectroscopy. The reduction in the number of amino groups observed by FTIR implied that amino groups of chitosan and its derivatives involved in crosslinking reactions during steam treatment. Steam treatment of the scaffolds resulted in decreasing of solubility of the scaffolds, indicating the formation of crosslinking by steam treatment. The percentage of weight loss and the degree of swelling of the steamed scaffolds depended on steaming temperatures. The pore structures of the scaffolds with and without steam treatment were open pore and columnar shape along the vertical direction.