Light scattering and NMR studies of Triton X-100 micelles in the presence of short chain alcohols and ethoxylates

Abstract

Micellar characteristics of nonionic surfactant p-tert-octyl-phenoxy polyethylene (9.5) ether (Triton X-100) in aqueous media containing short-chain alcohols and their ethoxylates CnEm (n=2, 4, 6 and m=0, 1, 2) were examined by dynamic light scattering (DLS) and nuclear magnetic resonance (NMR). The micelle size increased with the addition of C6Em and decreased when C2Em alcohols were added to Triton X-100 solution; the increase and decrease in the micellar size in the presence of varying amounts of C4Em alcohols depends on the number of polar ethoxylate groups. The results are supported by viscosity and cloud point data and explained on the basis of solvophobic interaction. The interaction and location of additives in micelles is examined by 1H and NOESY NMR. The studies indicate that C2Em molecules mostly remain in bulk water; C6Em molecules get solubilized toward the core of the aggregates, while C4Em molecules are localized in the shell region of micelle according to their octanol/water partition coefficient values.