The Rheology of Polymer Solutions in Ultrathin Films via a Combined Finite Elements-Brownian Dynamics Approach

通过有限元-布朗动力学组合方法研究超薄膜中聚合物溶液的流变学

• 批准号: 9731896
• 负责人: Eric Stefan Shaqfeh
• 金额: $ 20万
• 依托单位: Stanford University
• 依托单位国家: 美国
• 项目类别: Continuing Grant
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-09-01 至 2003-04-30
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9731896&HistoricalAwards=false
• 关键词: Rheology; Polymer; Solutions; Ultrathin; Films

ABSTRACT Proposal Number: CTS-9731896 Principal Investigator: Shaqfeh This is a grant to address a number of important problems in the study of polymer rheology that can be characterized as non-continuum or non-local. These are typically associated with the influence of boundaries or constrained environments on the stress-strain rate relationship. The burgeoning interest in these problems arises from the growing need to process materials at the molecular level. In most cases, new physical principles need to be applied to such problems because the most fundamental relationships, e.g. the relationship between the tension along a molecular backbone and the average extra stress in the mixture, need to be derived anew. Moreover these highly constrained flow fields are now only beginning to be experimentally interrogated, but the early data suggests that qualitatively new Theological behavior needs to be understood in these cases. Three problems that can serve as paradigms for theoretical model-building have been selected for study: a) the Couette-Poiseuille flow of flexible chains in solution when the pore or channel thickness is comparable to the radius of gyration of the polymers, b) the bulk shearing flow of polymer solutions near a boundary where the interface may contain adsorbed or grafted polymer layers, and c) the squeeze flow lubrication of "wet" polymer brush covered surfaces. The technique will be used is a novel hybrid scheme involving self-consistent flow calculations using HP adaptive finite elements and large scale Brownian dynamics simulations of bead-rod (Kramer's) chains.

摘要 提案编号：CTS-9731896 主要研究者：Shaqfeh 这是一个赠款，以解决一些重要的问题，在聚合物流变学的研究，可以被描述为非连续或非本地。 这些通常与边界或约束环境对应力-应变率关系的影响有关。 对这些问题的日益关注源于对在分子水平上处理材料的日益增长的需求。 在大多数情况下，需要将新的物理原理应用于此类问题，因为最基本的关系，例如，沿分子主链沿着的张力与混合物中的平均额外应力之间的关系，需要重新推导。 此外，这些高度受约束的流场现在才刚刚开始被实验研究，但早期的数据表明，在这些情况下，需要理解定性的新神学行为。选择了三个可以作为理论模型建立范例的问题进行研究：a）当孔或通道厚度与聚合物的回转半径相当时，溶液中柔性链的Couette-Poietille流动，B）界面附近聚合物溶液的本体剪切流动，其中界面可以包含吸附或接枝的聚合物层，和c）“湿”聚合物刷覆盖表面的挤压流润滑。 该技术将被用来是一种新的混合方案，涉及自洽流计算使用HP自适应有限元和大规模布朗动力学模拟珠棒（克雷默的）链。