表面活性剂-纳米颗粒相互作用与智能体系的构建(Ⅲ)相反电荷表面活性剂-纳米颗粒相互作用(ii)——用常规表面活性剂构建刺激-响应性Pickering乳状液和Pickering泡沫

Interactions between surfactants and nanoparticles and the construction of smart systems(Ⅲ) Interactions between oppositely charged nanoparticles and ionic surfactants(ii) Construction of stimuli-responsive Pickering emulsions and Pickering foams by using

在水介质中,离子型表面活性剂能够通过静电相互作用吸附到带相反电荷的无机纳米颗粒表面,产生原位疏水化作用,使原本强亲水性的无机纳米颗粒转变为表面活性颗粒,进而能够吸附到油(空气)/水界面,稳定Pickering乳状液和Pickering泡沫。如果能够通过某种触发机制促使表面活性剂从颗粒表面脱附,就可以解除原位疏水化作用,于是颗粒恢复其原本具有的强亲水性,自油(空气)/水界面脱附,导致破乳和消泡。如果这种吸附-脱附作用能够多次循环,就得到了所谓的刺激-响应体系。本讲座将介绍如何利用常规商品表面活性剂和普通纳米颗粒例如纳米二氧化硅和纳米氧化铝颗粒等来达成这一目标,主要采用离子对形成触发机制和pH触发机制。

In aqueous media,ionic surfactants tend to adsorb at oppositely charged inorganic nanoparticle/water interface via electrostatic interaction.The originally strongly hydrophilic nanoparticles thus become surface active by means of the hydrophobization in situ,which can then adsorb at oil(air)/water interface to stabilize Pickering emulsions and Pickering foams.If the hydrophobization can be removed,or the surfactants can be made desorb from particle surface,via some triggers,the particles will lose surface activity and desorb from oil(air)/ water interface,resulting in demulsification and defoaming.If this process can be cycled for many times,stimuliresponsive Pickering emulsions/foams will be obtained.This lecture will discuss how to construct such stimuliresponsive systems by using commercial surfactants and ordinary nanoparticles such as silica nanoparticles and alumina nanoparticles,mainly triggered by ion pair formation and pH.