Presidential Faculty Fellows/Presidential Early Career Awards for Scientists and Engineers (PFF/PECASE): Atomistic-Level Studies of Complex Fluids

CTS-9629135近年来，分子模拟在理论上取得了很大进展，但重要的是要认识到，现有的方法仍处于起步阶段，在解决大规模问题之前，还需要做更多的工作。我目前正在进一步发展分子模拟背后的理论，并实施新的模拟方法来研究大分子。我特别感兴趣的是应用这些方法来研究受限几何结构中复杂大分子的平衡结构和热力学性质，如在多孔介质、表面或模型生物膜中。我还应用这些方法来研究浓缩和稀释聚合物溶液的相平衡，并在微观水平上研究简单流动中聚合物熔体的流变性。这些模拟提供了在原子水平上对这些系统的基本理解，从而导致改进的理论模型和新颖的工程应用。我们目前正在研究复杂的铰链分子在流体和随机介质中扩散的机制。为此，我开发了随机方法，试图模拟柔性分子通过这种介质的运动。对于几个模型系统，随机方法的结果与非平衡动态模拟的结果进行了比较，结果是有利的。我们还发现，低温保护剂的混合物可以以协同的方式作用，形成改进的和独特的低温保护剂。我们开发了定量描述这些发现的分子模型，从而为选择和设计新的低温保护剂系统提供了亟需的指导方针。我们在这一领域的工作不仅将对生命系统的保护产生影响，也将对医药产品的保护产生影响。我们的目标之一是设计用于长期储存蛋白质和酶的室温玻璃。例如，如果实现了这一目标，就有可能在室温下长时间储存疫苗，从而便利在冷藏成问题的欠发达地区使用和分发疫苗。大学教育必须包括以下几个要素：基本原理、现实应用、实验、自我激励和自主研究。这些要素并不是工程学科独有的；它们是任何完整教育计划的基本组成部分。有了现代技术和通信系统，我们比以往任何时候都更有可能将所有这些方面的教育纳入我们的本科生和研究生课程。我不仅致力于在化学工程系这样做，而且还致力于在全校范围内这样做。

ABSTRACT CTS-9629135 In recent years, much progress has been made in theory behind molecular simulations; it is important to recognize, however, that available methods are still in their infancy and that much more work will be necessary before large scale problems can be addresses. I am currently developing further the theory behind molecular simulations and implementing novel simulation methods for the study of macromolecules. I am particularly interested in applying such methods to investigate equilibrium structural and thermodynamic properties of complex macromolecules in confined geometrics, as in porous media, surfaces or as in model biological membranes. I am also applying such methods to study phase equilibria for both concentrated and dilute polymer solutions, and to investigate at a microscopic level the rheological properties of polymer melts in simple flows. These simulations have provided a fundamental understanding of these systems at the atomic level, thereby leading to improved theoretical models and novel engineering applications. We are currently investigating the mechanisms through which complex, articulated molecules diffuse in fluids and in random media. To this end, I have developed strochastic methods that try to mimic the motion of flexible molecules through such media. For several models systems, comparison of the results of the stochastic approach to those of non-equilibrium dynamic simulations have been favorable. We have also found that mixtures of cryoprotectants can act in a synergetic manner to form improved and unique cryoprotectants. We have developed molecular models that describe quantitatively these findings, thereby providing much needed guidelines for the selection and design of new cryoprotectant systems. Our work in this area will have an impact not only in the preservation of living systems, but also in that of pharmaceutical products. One of our goals is that of designing room-temperature glasses for long-term storage of proteins and enzymes. If that goal is achieved, it will be possible, for example, to store vaccines at room temperature for extended periods of time, thereby facilitating use and distribution in underdeveloped areas where refrigeration is a problem. A college education must comprise the following elements: fundamental principles, realistic applications, experimentation, self motivation and independent research. These elements are not unique to engineering disciplines; they are essential components of any complete educational program. More than ever, with modern technology and communication systems it is possible to incorporate all of these aspects of education into our undergraduate and graduate curricula. I am committed to doing so not only in the department of chemical engineering but also at a campus-wide level.