chitosan/poly(amide-imide) blend films: studies on thermal and mechanical stability, morphology, and biodegradability

A diacid monomer was synthesized by the condensation of l-tryptophan amino acid and pyromellitic dianhydride (pmda). the diacid was utilized for the synthesis of three types of poly(amide-imide)s (pais) using three different kinds of diamines. the synthesized monomer and pais were characterized using ft-ir, ^1h-nmr and ^13c-nmr spectroscopies and the pais were also used for the fabrication of chitosan (cs)/pai blend films. xrd patterns of the pais, cs and cs/pai blend films were also studied. thermal stability of pais, cs and cs/pai samples were studied using thermogravimetric analysis (tga). the blend samples showed a higher thermal stability compared to the cs film, especially at higher temperatures. morphology of the cs and blend cs/pai films were studied before and after the biodegradation by sem. the mechanical stability studies showed that blend cs/pai films had a proper mechanical strength and their young’s modulus increased compared to the pristine chitosan. the in vitro fungal colonization of diacid monomer, pais, pure cs and blend cs/pai samples were performed using aspergillus niger fungi. after biodegradation, the pure cs showed the highest weight loss of 21.2 wt % among the samples. the blend cs/pai samples also showed higher weight losses compared to the pure pais.