科研之友
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摘要
Five kinds of unsaturated carboxylic acid salts of chitosan were prepared by the semidry way including chitosan salicylate (a1), chitosan benzoate (a2), chitosan cinnamate (a3), chitosan acrylate (a4) and chitosan itaconate (a5). The products were characterized via FTIR and UV, the content of carboxylic acid in the unsaturated carboxylic acid salt of chitosan was determinated by the Kjeldahl method. The results showed that unsaturated carboxylic acid salts of chitosan were combined with salt bond between amino and carboxyl, the content of carboxylic acid in the unsaturated carboxylic acid salts was ranged from 40% to 70%. The crystalline morphology of these unsaturated carboxylic acid salts of chitosan were obtained by polarized optical microscopy. The results showed that the films of a2 and a5 obtained by a casting solvent vaporation technique had formed fractal crystal at 25 degrees C and RH = 65%. The crystalline morphology was closely related to the structures of unsaturated carboxylic acid salts of chitosan. The fractal crystal of a2 showed that the extended molecular chains were parallel to the long axis. The fractal crystal of a5 showed that the extended molecular chains were perpendicular to the long axis. The methods for controlling aggregation behavior of unsaturated carboxylic acid salts of chitosan had also been studied. It was feasible for the inter-conversion between aggregation and crystallization. The crystallization process of chitosan unsaturated carboxylic acid salts was explained by fractal theory, and the results showed that its aggregation behavior abide by the model of diffusions-limited aggregation.
