SELF-ASSEMBLY OF ALCOHOL ETHOXYLATE NONIONIC SURFACTANTS IN AQUEOUS-SOLUTION

Four alcohol ethoxylates with general formula CnEm (where C = methylen e or methyl, E = oxyethylene, n = 11, 13, 15 and 17 and m approximate to 40) have been synthesised by anionic polymerisation initiated by th e appropriate alcohol and characterised by gel-permeation chromatograp hy (GPC) and NMR spectroscopy. Their self-assembly in aqueous solution was investigated by surface tension and static and dynamic light scat tering. All four surfactants associated by a closed process to form mi celles. Critical micelle concentrations (c.m.c.), surface tensions at the c.m.c., molecular areas in the air/water interface at the c.m.c., and micelle association numbers were obtained and compared with corres ponding values previously measured for related surfactants. Phase diag rams for thermally reversible gelation of concentrated solutions were defined. Gels with copolymer concentrations up to 70 wt.% were isotrop ic when examined by polarised light microscopy, consistent with cubic symmetry.