Collaborative Research: Microrheology of colloidal glasses and gels

1235955 / 1236242PI：第一/布拉迪胶体凝胶为什么和如何形成？凝胶和玻璃之间的关系是什么？当粒子相互拥挤到动态停滞点时，就会出现这种状态。关于胶体胶凝的机制，特别是在中等到高颗粒体积分数和相对弱的吸引相互作用下，存在长期的争论。这项工作的目的是研究胶体玻璃和凝胶的微流变学，以确定这些状态之间是否存在直接关系。这项工作是通过光学捕获实验的发展和斯托克动力学模拟来完成的，这些模拟测量了胶体悬浮液中单个探针粒子的响应。由于胶体玻璃和凝胶的理论是微流变的，但迄今为止很少有研究在微观长度尺度上检验和验证这些理论，因此这项工作是及时的。胶体凝胶是一种不稳定的、非平衡状态的物质，影响消费者护理产品、农用化学品、涂料、颜料和油墨的保质期。可能是指颗粒以高浓度悬浮于流体相中的任何产品或材料。此外，玻璃和凝胶是在分子、大分子和胶体材料中普遍存在的物质状态。在这个项目中获得的见解对我们对许多材料的基本理解具有广泛的影响。通过对STEM学科背景不足的研究生的综合教育和专业培训，以及涉及本科生研究经验和教师研究经验的外展活动，这项工作增强了美国在化学和先进材料行业的创新能力。

1235955 / 1236242PI: Furst / BradyWhy and how do colloidal gels form? What is the relationship between gels and glasses, states that occur when particles crowd each other to the point of dynamic arrest? There is long-running debate regarding the mechanism of colloidal gelation, particularly at moderate to high particle volume fractions and relatively weak attractive interactions. The aim of this work is to investigate the microrheology of colloidal glasses and gels to determine whether there is a direct relation between these states. The work is accomplished through the development of optical trapping experiments and Stokesian dynamics simulations that measure the response of individual probe particles in colloidal suspensions. Since theories of colloidal glasses and gels are microrheological, but few studies to date have examined and attempted to validate these theories on microscopic length scales, such work is timely.Colloidal gels are an arrested, non-equilibrium state of matter that impact shelf life of consumer care products, agrochemicals, coatings, pigments and inks?potentially any product or material in which particles are suspended at high concentration in a fluid phase. Moreover, glasses and gels are ubiquitous states of matter in molecular, macromolecular and colloidal materials. The insights gained under this project have broad implications for our fundamental understanding of many materials. Through an integrated education and professional training of graduate students from underrepresented backgrounds in STEM disciplines and outreach activities involving undergraduate research experiences and research experiences for teachers, this work enhances the capacity for US innovation in the chemical and advanced materials industries.