Avaliação de géis obtidos a partir da acetilação da quitosana em meio heterogêneo

AUTOR(ES)

Garcia, Rosangela Balaban, Silva, Dayse Luzia Pinheiro da, Costa, Marta, Raffin, Fernanda Nervo, Ruiz, Naira Machado da Silva

FONTE

Química Nova

DATA DE PUBLICAÇÃO

2008

RESUMO

Chitosan was acetylated during 2, 5 and 10h and physical gels were obtained at different polymer concentrations in N,N-dimethylacetamide containing 5% of LiCl. Acetylation was confirmed by infrared spectroscopy and 13C NMR, and degrees of acetylation in the range of 0.82-0.91 were determined by NMR. The O-acetylation degree (0.12-0.15) was exclusively determined by a volumetric method. Rheological studies showed that the storage modulus values were smaller for the more acetylated samples and increased with the temperature and the polymer concentration. All the gels presented storage modulus superior to loss modulus, evidencing more elastic than viscous characteristics. The results obtained in this work suggest a gelation process based on a balance between O and N-acetylation and intermolecular bonds.

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