Zheng Raojun, Tian Jingjing, Binks Bernard P, Cui Zhenggang, Xia Wenshui, Jiang Jianzhong
The Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical & Material Engineering, Jiangnan University, 1800 Lihu Road, Wuxi, Jiangsu 214122, China.
Department of Chemistry, University of Hull, Hull HU6 7RX. UK.
J Colloid Interface Sci. 2022 Dec;627:749-760. doi: 10.1016/j.jcis.2022.07.085. Epub 2022 Jul 16.
Oil-in-dispersion emulsions can be stabilized by like charged particles and surfactant. Surfactant adsorbs at the oil-water interface to reduce the interfacial tension and endow the interface with charge, while particles remain dispersed in the aqueous phase to provide electrostatic repulsion between droplets and particles. Can weakly surface-active organic electrolytes adsorb at the oil-water interface and behave like surfactants in stabilizing oil-in-dispersion emulsions with like charged particles?
Symmetrical organic electrolytes, tetraalkylammonium bromides (RNBr), with either no or very low interfacial activity endowing oil droplets with charge were combined with alumina nanoparticles to stabilize emulsions. The effect of R chain length (varying from methyl to butyl) on the type and stability of emulsions was investigated.
Mixtures of high concentrations of short chain RNBr salts (R = methyl or ethyl) and alumina particles stabilise oil-in-water Pickering emulsions, whereas longer chain (R = propyl or butyl) analogues stabilize oil-in-dispersion emulsions assisted by alumina particles. Tetrapropylammonium and tetrabutylammonium cations adsorb at the oil-water interface reducing the interfacial tension and endowing the interface with charge. The stability of the oil-in-dispersion emulsions is dominated by the electrostatic repulsion between the droplets and between droplets and particles in the continuous aqueous phase.
分散油乳液可通过带相同电荷的颗粒和表面活性剂来稳定。表面活性剂吸附在油水界面以降低界面张力并使界面带电，而颗粒则分散在水相中以提供液滴与颗粒之间的静电排斥力。弱表面活性有机电解质能否吸附在油水界面并在与带相同电荷的颗粒一起稳定分散油乳液时表现得像表面活性剂？
将具有零或极低界面活性（赋予油滴电荷）的对称有机电解质四烷基溴化铵（RNBr）与氧化铝纳米颗粒混合以稳定乳液。研究了R链长度（从甲基到丁基变化）对乳液类型和稳定性的影响。
高浓度短链RNBr盐（R = 甲基或乙基）与氧化铝颗粒的混合物可稳定水包油型皮克林乳液，而较长链（R = 丙基或丁基）类似物则在氧化铝颗粒的辅助下稳定分散油乳液。四丙基铵和四丁基铵阳离子吸附在油水界面，降低界面张力并使界面带电。分散油乳液的稳定性主要由连续水相中液滴之间以及液滴与颗粒之间的静电排斥力决定。
