CAREER: Nanostructured Particle Stabilized Bicontinuous Emulsions: Formation Principles, Structure-Function Relationships and Biphasic Transport

乳液或泡沫等多相体系对许多工业过程和产品都很重要。溶解或悬浮的物质可以在相间相界面处相遇、反应、积累和进行相转移。Bijels是一种相对较新的材料类别，其中两个不同的相都通过互穿网络连续连接(而不是在另一个相中有一个相的孤岛)。在双凝胶中，通过在两相之间的界面形成致密的颗粒层来稳定这两个相。首席调查员最近发现了一种制作比耶尔的新工艺。这一过程极大地扩大了可使用的液体对的范围，并允许定制Bijel结构。本工作是关于如何控制和调节双凝胶的结构和性能的详细研究。此外，还将测量这些材料中的流体流动和传质，以评估它们在应用中的潜在用途。第三项研究将涉及在连续流动的两相化学反应中使用Bijel的演示。该项目将揭示决定双凝胶结构的原理，并将导致工业应用的新的和设计良好的多相材料。潜在的应用范围从化工厂的强化产品提纯到比耶尔中高附加值化学品的工业合成。针对初中生、高中生、本科生和研究生的广泛的教育和推广活动也被纳入研究计划。这项工作的目的是确定通过溶剂转移诱导相分离(条)形成的双连续界面堵塞的乳胶凝胶(Bijel)是否可以用于连续操作和高效的相转移过程。最初的工作将集中在对Bijel结构和性能的控制上。Bijels将由一系列经过表面修饰的功能性无机胶体颗粒形成，这些颗粒将被开发和表征。双凝胶的亲水/疏水性质和表面官能团的排斥/吸引特性有望决定双凝胶的结构和稳定性；这将通过纳米颗粒的表面改性、表面表征、双凝胶的形成以及双凝胶结构和机械性能的表征来进行测试。这项工作的第二个推力将决定如何调整比耶尔的机械性能，以承受驱动流动所需的压力。开发了一种增强纳米颗粒界面堵塞层的方案，并构建了一种工具来表征双凝胶中的压力驱动流动，并在流动条件下评估其结构完整性。研究的第三个方面涉及双凝胶中连续流动下的相转移过程。我们将演示双凝胶中的连续萃取，然后研究双凝胶中模型反应的相转移催化作用。教育和推广活动包括为高中生开发一门“水滴工程”课程，为本科生开发一门关于胶体和界面工程的课程，为研究生开发一门关于软物质纳米技术的课程，并在首席研究员的YouTube频道上扩展教学视频。该奖项反映了NSF的法定使命，并通过使用基金会的智力优势和更广泛的影响审查标准进行评估，被认为值得支持。

Multiphase systems such as emulsions or foams are important for many industrial processes and products. Dissolved or suspended materials can meet at interfaces between phases, react, accumulate, and undergo phase transfer. Bijels are a relatively new class of materials in which the two distinct phases are both continuously connected through interpenetrating networks (rather than having islands of one phase within another phase). In bijels, the two phases are stabilized by forming a densely packed layer of particles at the interface between phases. The principle investigator has recently discovered a new process for making bijels. This process expands dramatically the range of liquid pairs that can be used and allows the bijel structure to be tailored. The present work is a detailed study of how to control and tune bijel structure and properties. In addition, fluid flow and mass transfer within these materials will be measured to assess their potential use in applications. A third study will involve a demonstration of bijel use in a two-phase chemical reaction with continuous flow. This project will uncover the principles that determine the structure of bijels and will lead to new and well-designed multiphase materials for industrial applications. Potential applications range from enhanced product purification in chemical plants to industrial synthesis of high-value added chemicals in bijels. A broad range of educational and outreach activities aimed at middle school, high school, undergraduate and graduate students are also integrated into the research plans.The objective of this work is to determine whether bicontinuous interfacially jammed emulsion gels (bijels) formed by Solvent Transfer Induced Phase Separation (STRIPS) can be employed for continuously operated and efficient phase transfer processes. Initial work will focus on control over bijel structure and properties. Bijels will be formed with a selection of functional inorganic colloidal particles with surface modifications that will be developed and characterized. The hydrophilic/hydrophobic nature and the repulsive/attractive character of surface functional groups are expected to govern bijel architecture and stability; this will be tested through surface modification of nanoparticles, characterization of surfaces, bijel formation, and characterization of bijel structure and mechanical properties. A second thrust of the work will determine how the mechanical properties of bijels can be tailored to withstand the pressures needed to drive flow. A scheme for reinforcing the interfacially jammed layer of nanoparticles has been developed and a tool has been constructed to characterize pressure-driven flow in bijels and assess their structural integrity under flow conditions. The third aspect of the study involves phase transfer processes under continuous flow in bijels. Continuous extraction in bijels will be demonstrated, followed by study of phase transfer catalysis of a model reaction in a bijel. Educational and outreach activities include the development of a "droplet engineering" course for high school students, a course on colloidal and interfacial engineering for undergraduates, a course on soft matter nanotechnology for graduate students, and expansion of instructional videos on the principle investigator's YouTube channel.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.