CHITOSAN-DERIVED POLYMER-SURFACTANTS AND THEIR MICELLAR PROPERTIES

Chitosan derivatives, sulfated N-acyl-chitosan (S-C-n-chitosan) possessing various lengths of alkyl chain, were prepared, and the properties of their aqueous solutions were examined, The H-1-NMR spectrum of D2O solutions of S-C-12-chitosan showed broadening of the proton signals caused by aggregation of the alkyl chain, The solubility of a hydrophobic compounds, azobenzene, was small in the aqueous solutions of S-C-n-chitosan with shorter alkyl chains, but increased with increasing length of the chains above C-10, showing that micelles had been formed. The ESR spectrum of a spin probe, TEMPO, in an S-C-14-chitosan solution showed the existence of a hydrophobic region in the solution, but this region did not exist in the S-C-2-chitosan solution, The rigidity of this region was examined by using a spin probe, 16-doxyl-stearic acid, From these results, it was revealed that S-C-n-chitosan with longer alkyl chains formed a novel type of micelle called a ''polymer micelle,'' which was more stable than the ordinary micelles formed from low-molecular-weight surfactants.