EAPSI: Rheology and Coalescence Behavior of Oil-Water Interfaces Stabilized by Soy Lecithin

基于乳液的递送系统广泛适用于一系列商业应用（包括药物递送、提高石油采收率、个人护理产品和食品加工），因为这些先进的材料系统能够递送和控制释放有价值的活性化合物。聚结（两个液滴合并形成单个较大液滴的不稳定过程）是在前述商业应用中实施这些递送系统的不期望的限制因素。因此，系统的调查，提高目前的理解，导致液滴聚结的动态过程是至关重要的。该项目将与悉尼新南威尔士大学副教授帕特里克斯派塞博士合作进行，该EAPSI项目的目的是阐明吸附在油-水界面上的纳米颗粒-表面活性剂混合物如何影响界面流变学和观察到的相邻油-水界面之间的聚结行为。水珠据推测，表面活性剂在皮克林（颗粒稳定的）乳液中的存在可以显着改变油-水界面处的颗粒相互作用，从而提高乳液对聚结动力学的抵抗力。该理论将被探索用于由二氧化硅纳米颗粒（~500 nm直径）稳定的水包油型Pickering乳液。和卵磷脂（用于递送活性化合物的最广泛使用的表面活性剂之一）。将使用普渡大学开发的悬滴张力法程序研究二氧化硅纳米颗粒和卵磷脂分子在油-水界面处的共吸附和界面流变学的表征。将使用定制的微操作设备、光学显微镜和高速成像能力，通过与新南威尔士大学的帕特里克斯派塞教授合作，直接观察微米级油滴在相关时间尺度（1 ms）下的动态聚结过程。这项研究的预期成果将提供更好的理解和预测物理现象的能力，这些物理现象决定了基于模板乳液的递送系统的成功开发。该奖项是东亚和太平洋夏季研究所计划的一部分，由NSF和澳大利亚科学院共同资助，支持美国研究生的夏季研究。

Emulsion-based delivery systems are widely applicable to a range of commercial applications (including pharmaceutical drug delivery, enhanced oil recovery, personal care products, and food processing) because these advanced material systems enable the delivery and controlled release of valuable active compounds. Coalescence (a destabilization process where two liquid droplets merge to form single, larger droplet) is an undesirable limiting factor for implementing these delivery systems within the foregoing commercial applications. Therefore, systematic investigations which improve current understanding of the dynamic processes that lead to droplet coalescence are crucially important. This project will be conducted in collaboration with Dr. Patrick Spicer, an Associate Professor at the University of New South Wales in Sydney, Australia and a noted expert on the production of shaped and targeted droplet delivery systems.The objective of this EAPSI project is to elucidate how nanoparticle-surfactant mixtures adsorbed to oil-water interfaces impact the interfacial rheology and observed coalescence behavior between neighboring oil-in-water droplets. It has been hypothesized that the presence of surfactants in Pickering (particle stabilized) emulsions can significantly modify particle interactions at the oil-water interface and thus improve an emulsion's resistance to coalescence dynamics. This theory will be explored for oil-in-water Pickering emulsions stabilized by silica nanoparticles (~500 nm dia.) and lecithin (one of the most widely used surfactants for the delivery of active compounds). Characterization of the co-adsorption and interfacial rheology of silica nanoparticles and lecithin molecules at the oil-water interface will be studied using pendant drop tensiometry procedures developed at Purdue University. Direct observation of dynamic coalescence processes between micrometer-scale oil droplets at relevant timescales (1 ms) will be conducted using custom micromanipulation equipment, optical microscopy, and high-speed imaging capabilities available through collaboration with Prof. Patrick Spicer at the University of New South Wales. The expected outcomes of this research will provide improved capacity for understanding and predicting the physical phenomena which govern the successful development of template emulsion-based delivery systems. This award, under the East Asia and Pacific Summer Institutes program, supports summer research by a U.S. graduate student and is jointly funded by NSF and the Australian Academy of Science.