la6b02616_si_002.avi (24.98 MB)

Redox-Controllable Interfacial Properties of Zwitterionic Surfactant Featuring Selenium Atoms

Download (24.98 MB)
posted on 05.09.2016, 00:00 by Weiwei Kong, Shuang Guo, Shaoqi Wu, Xuefeng Liu, Yongmin Zhang
Control of interfacial properties (foaming and emulsification) plays an important role in industry. Here we developed a novel redox-responsive surfactant, 3-(11-benzylselanyl-undecyl)-dimethylammonium acetate (BSeUCB), using selenium atoms as an environmentally sensitive group. In a reduced state, BSeUCB aqueous solution showed good foaming and emulsification abilities as well as conventional betaine surfactants. After oxidization, BSeUCB transformed into a bola-type structure because of the presence of a new hydrophilic group (selenoxide), and thus the critical micellar concentration, equilibrium surface/interfacial tension, and molecular area at the interface correspondingly increase from 0.32 mM, 46.43 mN·m–1, 5.30 mN·m–1, and 0.61 nm2 to 4.98 mM, 59.15 mN·m–1, 18.29 mN·m–1, and 1.22 nm2, respectively, resulting in a greater amount of energy input required to produce foam or emulsion, and a less dense adsorption layer, i.e., poor foaming and emulsification ability. Such a conversion was reversibly controlled by simply adding a trace amount (<0.06 wt % of the dispersion) of oxidant (H2O2) and reductant (Na2SO3). The products of the redox reaction did not interfere in the switchability except at the first cycle. The oxidization was generally time-consuming, whereas the reduction was very fast.