高亲水性纳米二氧化硅颗粒稳定Pickering乳液

用未修饰的高亲水性纳米二氧化硅颗粒(SiO2 NPs)在其等电点附近制备Pickering乳液。结果表明，等电点(pH 2.7)条件下SiO2 NPs借助高能均质与油水界面剧烈混合，并在范德华引力的驱动下以弱吸附的状态在界面处负载，从而稳定得到O/W型Pickering乳液。增加SiO2 NPs的浓度或减小油相体积分数可提高单位油滴界面的颗粒负载率，增大连续相黏度并促进乳液液滴之间形成三维网络结构从而提高乳液稳定性。通过调节连续相的pH以促进SiO2 NPs表面的硅烷醇发生质子化与去质子化的转变，实现乳液多次pH响应循环。

Pickering emulsion stabilized solely by hydrophilic SiO2 Nanoparticles

Pickering emulsions were successfully stabilized by highly hydrophilic silica nanoparticles (SiO2 NPs) near the isoelectric points. We found that vigorous mixing of SiO2 NPs suspensions of with oil, van der Waals forces between particles and oil droplets are sufficient to trap SiO2 NPs in close proximity to oil-water interfaces when the pH of suspensions equal to isoelectric points, and O/W Pickering emulsions were stabilized. Increasing the concentrations of SiO2 NPs or decreasing the oil phase volume fractions leads to a higher particle absorbing amount at the oil/water interface, higher viscosity of the continuous phase as well as the formation of a three-dimensional network structure between the emulsion droplets, thereby improving the stability of the emulsions. The emulsions perform good pH responsiveness benefiting from the protonation and deprotonation of silanol on the surface of SiO2 NPs under varying pH.