Crystallization and glass formation in colloidal-hydrogel suspensions

胶体水凝胶悬浮液中的结晶和玻璃形成

• 批准号: 1609841
• 负责人: Alberto Fernandez-Nieves
• 金额: $ 30万
• 依托单位: Georgia Tech Research Corporation
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2016
• 资助国家: 美国
• 起止时间: 2016-08-15 至 2020-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1609841&HistoricalAwards=false
• 关键词: Crystallization; glass; formation; colloidal; hydrogel

Non-Technical AbstractAdvances in synthetic, experimental and modeling/simulation methodologies have considerably enhanced our understanding of materials. Yet, despite this remarkable progress, many outstanding challenges remain in our quest to understand how the properties of the basic material units or particles determine the properties at the macroscale. This work uses small soft particles to address this question. In particular, the project aims at understanding how single-particle deformability and compressibility affect formation of ordered and disordered solids. The research involves graduate and undergraduate students, and provides materials for enhancing existent soft matter physics courses, both at the theoretical and laboratory-work levels. We also exploit the natural connection between the science we address and food and cooking, to bring the research to the general public; this is achieved by bringing chefs and scientists together and organizing outreach events that include talks and demos by the speakers.Technical AbstractThis project uses colloidal hydrogels as model soft particles to address (i) the formation of disordered solids and how it depends on the single-particle softness, and (ii) elucidate how size mismatch and polydispersity affect crystallization in soft-particle suspensions. One focus is the relation between glass formation and jamming, and whether these are distinct mechanisms, and if so, in which way and in what parametric range are they at play, for formation of disorder solids made of colloidal hydrogels. Another focus is to unravel the relation between fragility, which quantifies the way the liquid approaches the glass, and single-particle elasticity. The third focus is to elucidate the mechanism enabling crystallization of polydisperse colloidal-hydrogel suspensions. Ultimately, the overarching goal of this research is to understand and eventually exploit how single-particle softness affects macroscopic behaviour. The techniques employed include 3D-static light scattering, as well as small angle neutron and X-ray scattering, to quantify the structure of the suspension, 3D-dynamic light scattering and rheology, to quantify the dynamics at different time and length scales, and osmosis, to determine the suspension osmotic pressure, an important state function for colloidal systems. The experimental work is complemented with computer simulations and numerical calculations.

非技术摘要合成、实验和建模/模拟方法的进步极大地提高了我们对材料的理解。然而，尽管取得了如此显著的进步，在我们寻求了解基本材料单元或粒子的性质如何决定宏观尺度的性质方面，仍然存在许多突出的挑战。这项工作使用细小的软粒子来解决这个问题。特别是，该项目旨在了解单粒子的变形性和可压缩性如何影响有序和无序固体的形成。这项研究涉及研究生和本科生，并为加强现有的软物质物理课程提供材料，无论是在理论层面还是实验室工作层面。我们还利用我们所研究的科学与食品和烹饪之间的自然联系，将研究带给普通公众；这是通过将厨师和科学家聚集在一起并组织包括演讲和演讲者演示的外展活动来实现的。技术摘要该项目使用胶体水凝胶作为软颗粒的模型，以解决(I)无序固体的形成以及它如何依赖于单颗粒柔软性，以及(Ii)阐明尺寸不匹配和多分散性如何影响软颗粒悬浮液中的结晶。一个焦点是玻璃形成和堵塞之间的关系，以及这些是否是不同的机制，如果是的话，它们以什么方式和在什么参数范围内起作用，形成由胶体水凝胶组成的无序固体。另一个焦点是解开脆性和单粒子弹性之间的关系。脆性是液体接近玻璃的量化方式。第三个重点是阐明多分散胶体水凝胶悬浮液的结晶机理。归根结底，这项研究的首要目标是了解并最终探索单粒子的柔软性如何影响宏观行为。所采用的技术包括三维静态光散射，以及小角中子和X射线散射，以量化悬浮液的结构，三维动态光散射和流变学，量化不同时间和长度尺度上的动力学，以及渗透，以确定悬浮液渗透压，这是胶体体系的重要状态函数。实验工作得到了计算机模拟和数值计算的补充。