UNS: Collaborative Research: Testing the paradigms of the colloidal glass: Novel concentration jump experiments and large scale computer modeling

CBET-1506072 McKenna，Gregory B.CBET-1506079 Zia，Roseanna N.Colloid是粒子在液体中的分散体，例如水，粒子非常小，不会很长时间分离。这种材料广泛用于油漆和油墨等商业产品。它们也被认为是制作眼镜的很好的模型材料。目前的工作是一项合作研究，将实验和大规模计算机模拟相结合，将提供对胶体玻璃行为的新的科学理解，并将与文献中关于类似条件下的分子玻璃的知识进行比较。研究生和高中生将参加这两个PIs机构的研究活动。理解复杂物质的动态阻止在软物质科学中是一个巨大的挑战。大多数关于堵塞附近的胶体系统的研究都假定与分子玻璃中的相应行为相同。然而，最近的研究揭示了胶体中的非平衡反应与通过Kovacs特征监测的玻璃动力学本质上的不同，即本征等温线、接近的不对称性和记忆效应。这项拟议的研究将通过一种新颖的实验和动态模拟相结合的方式来阐明这种差异的结构基础。结构和动力学将在类似于Kovacs分子玻璃形成系统实验的实验中确定。在这里，对刺激反应敏感的粒子将以恒定的数密度改变直径，以创造浓度跳跃的条件，以模拟科瓦奇标志性实验的温度跳跃。并发模拟将在Silico中产生类似的情况。实验和模拟将相互通知和验证，对干扰转变附近的胶体动力学的联合询问将潜在地产生对软物质中停滞状态的变革性理解。在更广泛的意义上，这是两个非常不同的PI的合作。其中一位是分子玻璃实验物理方面的专家，特别是老化。另一位是大规模计算机模拟方面的专家，重点是胶体系统。其结果为研究生提供了独特的跨学科培训，包括计算物理和实验物理，加深了他们对分子和胶体玻璃的动力学和老化的基础知识。此外，妇女和代表性不足的少数群体将作为本科生和研究生研究人员发挥核心作用。

CBET - 1506072 McKenna, Gregory B.CBET - 1506079 Zia, Roseanna N.Colloids are dispersions of particles in a liquid, such as water, and the particles are so small that they do not separate for very long times. The materials are widely used in commercial products such as paints and inks. They are also believed to be a good model materials for glasses. The present work is a collaborative study that combines experiment and large scale computer simulations that will provide novel scientific understanding of the behavior of colloidal glasses and comparisons will be made with knowledge from the literature concerning molecular glasses in similar conditions. Graduate and high school students will participate in the research activities at both PIs' institutions.Understanding dynamical arrest in complex matter is a great challenge in soft matter science. Most study of colloidal systems near jamming assumes parity with corresponding behavior in molecular glasses. Yet, recent studies reveal non-equilibrium responses in colloids that differ qualitatively from glassy dynamics as monitored via the Kovacs signatures, viz., the intrinsic isotherm, the asymmetry of approach, and the memory effect. The proposed study will illuminate the structural underpinnings of such differences through a novel combination of experiment and dynamic simulation. The structure and dynamics will be determined in experiments analogous to the Kovacs experiments for molecular glass-forming systems. Here stimulus-responsive particles will change diameter at constant number density to create concentration-jump conditions to mimic the temperature-jumps of the Kovacs signature experiments. Concurrent simulations will effect similar conditions in silico. Experiment and simulation will inform and validate each other and the joint interrogation of the colloid dynamics near to the jamming transition will potentially create a transformative understanding of arrested states in soft matter. In a broader sense, this is a collaboration of two very different PIs. One is an expert in the experimental physics of molecular glasses, especially aging. The other is an expert in large scale computer simulation, with emphasis on colloidal systems. The result provides unique cross-disciplinary training to graduate students in both computational and experimental physics, deepening their knowledge of the fundamentals of dynamics and aging of molecular and colloidal glasses. Further, women and under-represented minorities will play a central role as undergraduate and graduate researchers.