RUI: Dynamic Light Scattering Test of Bond Model Predictions for the Dynamics of Network-forming Liquids near the Glass Transition

无定形固相原则上是所有液体所特有的，尽管某些液体在冷却时有结晶的倾向。然而，液体在凝固之前变稠的方式在不同的材料中有很大的不同。过去的研究表明，过冷的玻璃形成液体的动力学与其化学结构和称为“脆性”的热力学性质之间存在明确的联系。在这个项目中，动态光散射，拉曼光谱和差示扫描量热法正在应用于探测液体动力学如何直接受到网络形成系统中产生的简单结构变化的影响。结果将形成一个精确的测试目前可用的建议的热力学模型（债券模型）。工作将由研究生（MS）和本科生进行，提供实践研究经验，以增加他们的科学教育。非技术性文摘技术的蓬勃发展依赖于对材料新特性的开发。其中，玻璃质材料具有独特的机械，光学和电气性能的重要性，许多国家的最先进的设备。然而，为了实现它们的潜力，玻璃质材料必须从液态固化而不发生结晶。这就需要了解液体到玻璃的转变，特别是了解液体的化学结构如何影响增稠过程本身。在这个项目中，玻璃形成液体散射的可见光被用来在微观水平上监测这一增稠过程。一系列的玻璃形成液体进行研究，其中的化学结构可以系统地改变，无论是增加或减少存在于液体中的化学键的平均数。随着结构的每次修改，将评估液体动力学性质的相应变化，以测试基于存在的平均键数的简单模型的预测。研究生（MS）和本科生将进行这项研究，作为培养下一代专业科学家的手段。

Technical AbstractThe amorphous solid phase is, in principle, endemic to all liquids despite a propensity for some liquids to crystallize when cooled. However, the manner in which a liquid thickens in advance of solidification is vastly different among different materials. Past research has demonstrated a clear link between the dynamics of a supercooled, glass-forming liquid and its chemical structure and thermodynamic properties referred to as "fragility". In this project, dynamic light scattering, Raman spectroscopy and differential scanning calorimetry are being applied to probe how liquid dynamics are directly affected by simple structural changes created in network-forming systems. The results will form a precise test of a proposed thermodynamic model (Bond Model) presently available. Work will be carried out both by graduate (MS) and undergraduate students providing hands-on research experience to augment their science education. Non-technical AbstractTechnology thrives on exploiting the novel properties of materials. Among these, glassy materials possess unique mechanical, optical and electrical properties of importance for many state-of-the-art devices. However, for their potential to be realized, glassy materials must be solidified from the liquid state without crystallization occurring. This then requires an understanding of the liquid-to-glass transition and in particular an understanding of how chemical structure of the liquid affects the thickening process itself. In this project, visible light scattered by a glass-forming liquid is used to monitor this thickening process on a microscopic level. A series of glass-forming liquids are to be investigated in which the chemical structure can be systematically altered by either increasing or decreasing the average number of chemical bonds present in the liquid. With each modification of the structure, the corresponding changes in dynamical properties of the liquid will be assessed to test predictions of a simple model based upon the average number of bonds present. Graduate (MS) and undergraduate students will conduct this research as means of training the next generation of professional scientists.