Evaluation of gels obtained from acetylation of chitosan in heterogeneous medium

Química Nova

Costa, Marta¹  Universidade Federal do Rio Grande do Norte, Natal, Brasil¹  Centro de Pesquisa Leopoldo A. Miguez de Mello, Rio de Janeiro, Brasil¹  Raffin, Fernanda Nervo¹  Silva, Dayse Luzia Pinheiro da¹  Garcia, Rosangela Balaban¹  Ruiz, Naira Machado da Silva¹ 

关键词: chitosan;    gel;    rheology.;   

DOI  :  10.1590/S0100-40422008000300004

学科分类：化学（综合）

来源: Sociedade Brasileira de Quimica

【 摘 要 】

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.

【 授权许可】

Unknown