Enhanced Aggregation of Stimuli Responsive Surfactants by Esterolytic Reactions.

Thioester surfactants, [CHN(CH)(CH)SCOCH] Br (CmSAc, m = 4, 11, 12), yielded thiol surfactants via thiol-thioester exchange upon addition of dithiothreitol in aqueous solution. The thiolthioester exchange reaction was enhanced in a micellar system owing to the concentration effect. The enhanced aggregation upon deprotection of the thioacetate group was observed by dynamic light scattering measurements. The thiol surfactants yielded disulfide-linked gemini surfactants upon air oxidation and incubation with hydrogen peroxide. In contrast, the thiol surfactants yielded thioester double-tailed products by esterolytic reactions with p-nitrophenyl hexanoate. The introduction of an alkyl chain to the second side chain significantly decreased the critical micelle concentration and induced the micellar growth.