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

胶体是粒子在液体（如水）中的分散体，这些粒子非常小，它们在很长一段时间内不会分离。这些材料广泛用于油漆和油墨等商业产品。它们也被认为是玻璃的良好模型材料。目前的工作是一项结合实验和大规模计算机模拟的合作研究，将为胶体玻璃的行为提供新的科学理解，并将与文献中关于类似条件下分子玻璃的知识进行比较。研究生和高中生将在两所学院参与研究活动。理解复杂物质中的动力学阻滞是软物质科学的一个重大挑战。大多数对接近干扰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，最近的研究表明，胶体中的非平衡反应在性质上不同于通过Kovacs特征监测的玻璃动力学，即内在等温线、接近的不对称性和记忆效应。提出的研究将通过实验和动态模拟的新颖结合来阐明这种差异的结构基础。结构和动力学将在类似Kovacs实验的分子玻璃形成系统的实验中确定。在这里，刺激响应粒子将以恒定的数量密度改变直径，以创造浓度跳跃条件，以模拟Kovacs标志性实验的温度跳跃。并行模拟将在计算机上产生类似的效果。实验和模拟将相互通知和验证，并且对靠近干扰转变的胶体动力学的联合询问将潜在地创造对软物质中阻滞状态的变革性理解。从更广泛的意义上说，这是两个非常不同的pi的合作。一位是分子玻璃实验物理学方面的专家，尤其是老化方面。另一位是大规模计算机模拟专家，重点是胶体系统。结果提供了独特的跨学科训练研究生在计算和实验物理，加深他们的动力学和老化的分子和胶体玻璃的基础知识。此外，妇女和代表性不足的少数民族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.