Crystallization and glass formation in colloidal-hydrogel suspensions

合成、实验和建模/模拟方法的进步大大提高了我们对材料的理解。然而，尽管取得了显著的进展，但在我们寻求理解基本物质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。这项工作使用小的软颗粒来解决这个问题。特别是，该项目旨在了解单颗粒的变形性和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，并提供材料，以提高现有的软物质物理课程，无论是在理论和实验室工作水平。我们还利用我们所研究的科学与食物和烹饪之间的自然联系，将研究成果带给公众;这是通过将厨师和科学家聚集在一起，并组织包括演讲者的演讲和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模型软颗粒来解决（i）无序固体的形成以及它如何依赖于单颗粒的柔软性，和（ii）阐明了尺寸失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，如果是这样，在何种方式和在什么参数范围内，他们在发挥作用，形成无序固体胶体水凝胶。另一个重点是解开脆弱性之间的关系，它量化了液体接近玻璃的方式，以及单颗粒弹性。第三个重点是阐明多分散胶体水凝胶悬浮液的结晶机制。最终，这项研究的总体目标是了解并最终利用单粒子柔软度如何影响宏观行为。所采用的技术包括3D静态光散射，以及小角度中子和X射线散射，以量化悬浮液的结构，3D动态光散射和流变学，以量化不同时间和长度尺度的动态，以及渗透，以确定悬浮液渗透压，胶体系统的重要状态函数。实验工作辅以计算机模拟和数值计算。

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.