Study on radiation-induced grafting of hydrophilic monomers onto chitosan

The graft polymerization of 2‐Hydroxyethyl acrylate, 2‐Hydroxyethyl methacrylate, and N‐vinylpyrrolidone onto chitosan in aqueous solution initiated by γ‐ray irradiation was carried out. The effect of various conditions such as the absorbed dose, concentration of monomer, and solvent on grafting was investigated. The grafting yield increased with the increase in absorbed dose. The degree of grafting increased with increase in the radiation dose. The obtained graft copolymers showed the solubility in water in wide pH interval. The interactions between grafted chitosan copolymers with sodium dodecyl sulfate (SDS) were studied in an aqueous solution. It was found that there is a narrow molar ratio of SDS/cation (∼ 0.40–0.70) depending on different grafted copolymers, at which the turbidity of SDS‐grafted chitosan complex has a maximum due to the formation of water insoluble interpolymer aggregates via the SDS attached on the polymer chain. The turbidity falls sharply with the further addition of excessive SDS, which forms micelle in the solution and causes the de‐aggregation of the interpolymer aggregates and also because of the precipitation of complexes and returns to the original level. The morphologic properties of thin films of SDS‐ grafted chitosan complex were investigated. It was observed that upon heating the insoluble complex of SDS and grafted chitosan in water, superstructures were formed. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008