Connecting Interfacial Properties to Emulsion Stability for Complex Particle-Laden Interfaces

CBET 1437864乳状液和泡沫存在于许多具有工业和生物重要性的过程中。食品、化妆品、制药、医药、聚合物以及石油和天然气行业经常加工乳液和泡沫。从乳液和泡沫中制造有用的、寿命长的产品的关键要求之一是通过防止液滴或气泡相互结合来确保它们的稳定性，这可能会降低产品质量。该项目将使用研究人员开发的微张力计来检查液滴和气泡界面的物理和化学特性，并在严格控制的条件下确定这些特性如何影响两个液滴的结合。使用微张力计，研究人员将检查合并过程，同时获取有关液滴界面特征的信息。将考察乳化剂的影响，这些乳化剂可以通过吸附到液滴界面并防止团聚来稳定乳液。然后，该团队将探索一种新型稳定剂的有效性，该稳定剂由包裹着表面活性剂的纳米颗粒组成。这一结果将为配制乳液和泡沫并设计加工系统的科学家和工程师提供新的工具。微张力计将用于研究半径在50至150微米之间的小液滴和气泡的界面流变性。通过监测气泡内部压力和界面面积，可以确定界面的动态表面张力和界面弹性。为了获得表面活性剂在界面上的吸附受到动力学限制的条件，将通过添加流过界面的对流来修改设备。然后，微张力仪将被用来观察具有相同曲率、成分和历史的两个液滴或气泡的合并，这将有助于消除在其他合并测量中出现的歧义。结果将被用来确定界面流变性和聚结之间的关系。将使用易于吸附到界面上的表面活性剂包裹的纳米颗粒的模型系统来表征颗粒界面对聚结的影响。

CBET 1437864Emulsions and foams occur in many processes of industrial and biological importance. The food, cosmetic, pharmaceutical, medicinal, polymer, and oil and gas industries routinely process emulsions and foams. One of the key requirements in making useful, long-lived products from emulsions and foams is to guarantee that they are stable by preventing the drops or bubbles from coalescing with each other, which can degrade product quality. This project will use a microtensiometer developed by the investigators to examine the physical and chemical properties of drop and bubble interfaces and determine how those properties influence the coalescence of two drops under carefully controlled conditions. Using the microtensiometer, the investigators will examine the coalescence process while simultaneously acquiring information about the interfacial characteristics of the drops. The influence of emulsifiers that can stabilize emulsions by adsorbing onto drop interfaces and preventing coalescence will be examined. Then, the team will explore the effectiveness of a novel stabilizer consisting of nanoparticles coated with surfactants. The results will provide new tools to scientists and engineers who formulate emulsions and foams and design systems to process them.A microtensiometer will be used to study the interfacial rheology of small drops and bubbles with radii between 50 and 150 micrometers. By monitoring the pressure inside the bubble and the interfacial area, the dynamic surface tension and interfacial elasticity of the interface can be determined. To access conditions where the adsorption of surfactants onto the interface is kinetically limited, the device will be modified by adding a convective flow past the interface. The microtensiometer will then be used to observe the coalescence of two drops or bubbles with identical curvature, composition and history, which will help eliminate ambiguities that occur in other coalescence measurements. The results will be used to ascertain the relationship between interfacial rheology and coalescence. The effects of particle-laden interfaces on coalescence will be characterized using a model system of surfactant-coated nanoparticles that readily adsorb onto interfaces.