The structure of micelles of mixed anionic surfactants and their complexes with cationic starch studied by SANS

Complete text of publication follows. The aim of this study was to determine the composition and structure of mixed micelles of different chain length alkanoates (sodium octanoate - sodium hexadecanoate) and the structure of cationic starch/mixed surfactant complexes. The cationic starch (CS) was a potato starch having 2-hydroxy-3-trimethylammoniumpropyl groups as substituents. It was partly depolymerized by oxidizing with sodium hypochlorite. Its molecular mass is 104 - 106 and the degree of substitution is 0.80. The small-angle neutron scattering experiments were perform on solutions of different alkanoate mixtures. The complexation of cationic starch with surfactant mixtures was studied by using different CS/surfactant ratios as well as using surfactant mixtures of different chain-length difference. Deuterated and protonated surfactants were used. The formation of mixed micelles and cationic starch/surfactant complexes is observed. The structure, composition, and electrical charge of mixed micelles versus chain length difference and molar ratio of alkanoates are determined. Structural parameters of cationic starch/surfactant complexes are evaluated. (author)