响应型Pickering乳液的构建、调控及介电行为研究

In order to meet the requirements of emulsions under different conditions, it is important to develop stimuli-sensitive emulsifier and achieve the reversible modulation and real-time detection of emulsions. The negatively charged silicon dioxide nanoparticles in combination with a trace amount of ferrocene (fc)-containing cationic surfactant are used as particulate stabilizers for electric-field-responsive Pickering emulsions to achieve remote control and real-time detection of emulsion stabilization. At the same time, the dielectric behavior of emulsions during phase separation is studied. The influences of volume ratio of oil-water phase, salt concentration, emulsifier particle concentration, zeta potential and three-phase contact angle on emulsion properties will be studied by dynamic light scattering (DLS) cryo-transmission electron microscopy (cryo-TEM), etc. And the stabilization mechanism will be proposed. Then the electrochemical methods are used to modulate the emulsion properties, which will not destroy the studied system. The electrochemical methods will be helpful to achieve reversible control of emulsion properties and to avoid the influence of additives and the opaque systems. At the same time, electrical impedance spectroscopy (EIS) is applied to study the stability and phase behavior of emulsions, which will enrich the electrical response model resulting from flocculation.

满足乳液在不同条件下使用需求，发展刺激敏感型乳化剂，实现乳液稳定性的可逆调控和实时检测，是当前乳液研究的重要课题。本项目拟将荷负电的二氧化硅纳米颗粒与含二茂铁功能基团的阳离子表面活性剂静电结合，将其作为乳化剂构建电场响应型Pickering乳液，研究乳液相分离过程中介电行为的变化规律，实现乳液稳定性的远程电场调控及实时检测。通过利用动态光散射（DLS）、低温透射电镜（cryo-TEM）等先进表征手段，系统研究油水相体积比、盐浓度、乳化剂颗粒浓度、zeta电位和三相接触角等因素对乳液性质的影响规律，探索此类纳米颗粒乳化剂稳定乳液的机理。同时，利用对体系无破坏性的电化学方法对乳液性质进行调控，将有助于实现乳液稳定性的远程控制，解决外加物质导致体系破坏及透明度较低乳液稳定性的调控问题。而利用可在线测量的电化学阻抗谱，是乳液稳定性实时检测方面的突破和创新，是对絮凝引起电化学响应模型理论的极大丰富。

满足乳液在不同条件下使用需求，发展刺激敏感型乳化剂，实现乳液稳定性的可逆调控和实时检测，是当前乳液研究的重要课题。本项目使用功能分子对纳米颗粒进行非共价改性，并将改性后颗粒作为稳定剂制备Pickering乳液。基于功能分子的刺激响应性，改性纳米颗粒的亲疏水性可通过外界刺激进行调节，因而赋予所稳定Pickering乳液环境响应性。而且，具有氧化还原活性荧光分子的引入可实现乳液界面上颗粒吸附情况的直观检测，这种不额外引入荧光分子发生的荧光行为在Pickering乳液荧光标记方面具有重要的潜在应用。在此基础上，研究了此类乳液稳定机理、刺激响应性的触发机制和应用，实现了乳液稳定性的可逆调控。同时，利用可在线测量的电化学阻抗谱法（EIS），研究非共价表面改性二氧化硅纳米颗粒制备水包油（O/W）Pickering乳液的稳定性，通过对EIS获得的乳液频率响应数据模拟分析，观察到乳液在Nyquist图中的特征是一个半圆，乳液的拟合阻抗值随液滴的平均粒径减小而减小，乳液稳定性增加。研究表明，EIS可用于实时表征改性二氧化硅颗粒制备的O/W型Pickering乳液稳定性，对乳液的贮存和使用具有重要意义。