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

RUI：键模型预测玻璃化转变附近网络形成液体动力学的动态光散射测试

• 批准号: 0906640
• 负责人: David Sidebottom
• 金额: $ 37万
• 依托单位: Creighton University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-09-01 至 2016-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0906640&HistoricalAwards=false
• 关键词: RUI; Dynamic; Light; Scattering; Test

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.

技术摘要：非晶固相原则上是所有液体所特有的，尽管有些液体在冷却时有结晶的倾向。然而，液体在凝固前变稠的方式在不同的材料之间有很大的不同。过去的研究已经证明了过冷玻璃形成液体的动力学与其化学结构和被称为“易碎性”的热力学性质之间的明确联系。在这个项目中，动态光散射、拉曼光谱和差示扫描量热法被应用于探测在网络形成系统中产生的简单结构变化如何直接影响液体动力学。这些结果将形成一个目前可用的提议的热力学模型（键模型）的精确测试。工作将由研究生（硕士）和本科生进行，提供实践研究经验，以增加他们的科学教育。摘要技术在开发材料的新特性上蓬勃发展。其中，玻璃材料具有独特的机械、光学和电学特性，对许多最先进的设备至关重要。然而，为了实现它们的潜力，玻璃材料必须从液态凝固而不发生结晶。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层面上监测这个增厚过程。将研究一系列形成玻璃的液体，它们的化学结构可以通过增加或减少液体中存在的化学键的平均数目来系统地改变。随着结构的每次修改，液体动力学性质的相应变化将被评估，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。