基于液滴电聚并的乳液稳定性的研究

Emulsion droplets are ubiquitous in our daily life products, industrial products as well as emerging droplet-microfluidic-based applications, such as digital PCR, and high throughput drug screening. Quick characterization of the emulsion stability can speed up the formulation design of the product by reducing the development time and cost; enhance the safety of food through minimizing the use of emulsifiers. In addition, characterizing the emulsion stability in a fast manner can help screen the appropriate type and concentration of emulsifiers, which is crucial for applying droplet microfluidics in clinical applications. To advance this field, we propose a method to rapidly characterize the stability of emulsions stabilized by different emulsifiers through studying the electro-coalescence of droplets. Using a custom-built micro-device to accurately control the environmental conditions, adsorption time of emulsifiers and other related parameters, we propose to systematically study the dependence of critical voltage, which triggers the electro-coalescence, on type, concentration of emulsifier as well as size, electrical conductivity of droplets. We will explore the mechanism behind the electro-coalescence and further propose a physical model to calculate the critical disjoining pressure which determines the stability of emulsions. Our proposed work could be beneficial to any applications involved the emulsion droplets which includes food, cosmetics, pharmaceutics and applications based on droplet microfluidics.

乳液微液滴常见于日常生活产品、工业产品以及诸如数字核酸扩增技术（dPCR）、高通量药物筛选等微流控技术应用中。乳液液滴稳定性的快速测定能加快产品配方换代，减少研发时间与成本；降低乳化剂的使用，提高食品安全性；同时，诸多液滴微流控技术的应用亟需快速测定乳液稳定性从而来筛选出合适的乳化剂种类与浓度。本项目拟通过研究液滴电聚并现象，提出一种快速测定乳液稳定性的技术方法。该方法通过设计一个微装置来精细控制环境条件、乳化剂吸附时间等因素对实验的影响，并在该装置上系统地研究触发液滴电聚并的临界电压与乳化剂种类、浓度以及液滴的物性参数的关系。基于液滴电聚并的实验结果，该项目拟研究电聚并背后的物理机理，并进一步提出计算决定乳液稳定性的分离压力的模型，从而实现乳液稳定性的快速鉴定。该提出方法快速、简便、成本低、可行性高，研究成果将对食品、化妆品、药剂等配方设计以及基于液滴微流控的实际应用有着至关重要的意义。

微液滴常见于日常生活产品、工业产品，同时它也是诸如数字核酸扩增技术、高通量药物筛选等微量化反应的重要单元。研究液滴稳定性的快速测定能加快这些应用产品的配方迭代，减少研发时间与成本；降低乳化剂的使用，提高食品安全性；同时，诸多基于微液滴的应用亟需快速测定稳定性从而来筛选出合适的稳定剂的种类与浓度。在该项目中，我们系统地研究了以表面活性剂等两亲性分子及颗粒作为稳定剂来形成乳液液滴、皮克林乳液、液体弹珠，并探讨了电场触发液滴发生电聚并的物理现象。同时，我们探究了电聚并的物理机理，阐明了两亲性分子及颗粒对液滴稳定性的影响机制。为我们鉴定液滴稳定性提供了指导和新途径。该项目在执行期内产生的成果包括在Advanced Materials、Advanced Functional Materials、Angewandte Chemie, Small等重要学术期刊上发表论文15篇，其中以该基金为第一标注的有10篇，第二标注的有5篇。申请发明专利5项。该项目的研究成果将对食品、化妆品、药剂等配方设计以及基于微液滴的应用研究有着至关重要的意义。