Designing Colloidosomes with Unjammed Interfaces

乳状液由悬浮在第二个不相容的液体中的液滴组成，如水中的油滴。Pickering乳液是一种特殊的乳液，其中的小颗粒位于液滴和周围液体之间的界面上。这些小颗粒在液滴界面的存在确保了液滴不会相互结合并打破乳状液。这些乳剂通常用于商业化妆品、食品以及3D打印等较新的应用中。通常，液滴的界面几乎完全被粒子覆盖，这基本上是通过在液滴周围创建盔甲来阻止合并。然而，完全涂覆液滴需要大量的小颗粒，这对环境构成了挑战，并且限制了制备具有新特性的乳液的能力。为了解决这些问题，该项目将研究具有不同表面属性的颗粒组合如何在较低的颗粒浓度下创建防止聚结的界面。这项研究将研究界面性质与单个液滴和液滴集合的行为之间的关系，以确定稳定乳状液的最佳界面配置。此外，研究小组将为德克萨斯理工大学周围地区的高中开发几个流动实验室，向学生传授许多常见商业产品背后的科学知识。目前，胶体上的颗粒界面主要影响液滴的行为，因为界面堵塞。这个项目背后的假设是，胶体的行为可以通过使用具有电荷双分散性或润湿性的颗粒来创建具有高界面粘弹性的无堵塞界面来改变。将进行一系列结合界面流变学、微流体学和图像分析的实验来验证这一假设。首先，该项目将表征一系列高粘弹性、中等表面覆盖率界面的流变性和微观结构。然后，使用微流控技术将这些界面复制到胶体上。利用特定的微流体几何构型，胶体小体将被迫变形、破碎和结合。胶体的性质将与界面流变性测量、带有简单液体和/或堵塞界面的液滴进行比较，并与理论预测进行比较。由此得到的数据集将描述未受干扰的胶体的行为及其潜在的用途。创建具有可控界面的胶体将确定界面弹性和未堵塞颗粒界面的产量如何影响胶体行为，提高操作胶体系统用于重要应用的能力。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。

Emulsions consist of liquid droplets that are suspended in a second, immiscible liquid, such as oil droplets in water. Pickering emulsions are a special kind of emulsion in which the small particles sit at the interface between the droplets and the surrounding liquid. The presence of these small particles at the droplet interface ensures that the droplets do not coalesce with each other and break the emulsion. These emulsions are commonly found in commercial cosmetics, foodstuffs, and in newer applications like 3D printing. Typically, the interface of a droplet is nearly completely covered with particles, which stops coalescence by essentially by creating armor around the droplet. However, coating the droplets completely requires a large number of small particles, which poses an environmental challenge, and it limits the ability to make emulsions with novel properties. To address these issues, this project will study how combinations of particles with different surface properties can create interfaces that prevent coalescence at lower particle concentrations. The research will examine the relationship between the properties of the interface and the behavior of individual drops and collections of drops to determine the best optimal interface configuration to stabilize emulsions. Additionally, the research team will develop several traveling labs for high schools in the region surrounding Texas Tech University that will educate students about the science behind common many commercial products.Currently, particle interfaces on colloidosomes primarily impact droplet behavior due to interfacial jamming. The hypothesis underlying this project is that colloidosomes’ behavior can be modified by creating unjammed interfaces with high interfacial viscoelasticity using particles with bidispersity of charge or wettability. A series of experiments that combine interfacial rheology, microfluidics, and image analysis will be conducted to examine this hypothesis. To start, the project will characterize rheology and microstructure of a range of highly viscoelastic, moderate surface coverage interfaces. Then, these interfaces will be replicated on colloidosomes using microfluidic techniques. The resultant colloidosomes will be forced to deform, breakup, and coalesce using specific microfluidic geometries. The properties of the colloidosomes will be compared to interfacial rheology measurements, drops with simple liquid and/or jammed interfaces, and to theoretical predictions. The resulting data set will characterize behavior of unjammed colloidosomes and their potential utility. Creating colloidosomes with controllable interfaces will establish how interfacial elasticity and yield of unjammed particle interfaces affects colloidosome behavior, increasing the capability to manipulate colloidosome systems for important applications.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.