Radiation-induced degradation of carboxymethylated chitosan in aqueous solution

Aqueous solutions of carboxymethylated chitosan (CM-chitosan) were radiated with gamma-ray in various conditions. The degradations of CM-chitosan were faster in the presence of nitrous oxide or hydrogen peroxide, but it was inhibited obviously after adding isopropanol because of the changes of the concentration of hydroxyl radicals in above different conditions. The radiation chemical yields of CM-chitosan degradation were found to decrease at lower pH in which the polymer chains tend to coiled conformation. Intrinsic viscosity of CM-chitosan decreased faster than that of carboxymethylated chitin, indicating that amino groups could enhance the reactivity. FTIR and UV spectra showed that main chain structures of CM-chitosan were remained and some carbonyl/carboxyl groups were formed during the degradation. The data of EA indicated the contents of C/N were increased, which suggested the elimination of partial amino groups during radiation. (c) 2006 Elsevier Ltd. All rights reserved.