The Rheology Of Polymer Solutions In Ultrathin Films Via A Combined Finite Elements-Brownian Dynamics Approach

通过组合有限元布朗动力学方法研究超薄膜中聚合物溶液的流变学

• 批准号: 9732535
• 负责人: Bamin Khomami
• 金额: $ 15万
• 依托单位: Washington 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 2002-12-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=9732535&HistoricalAwards=false
• 关键词: Rheology; Polymer; Solutions; Ultrathin; Films

ABSTRACT Proposal Number: CTS-9732435 Principal Investigator: Khomani 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-9732435 首席研究员：Khomani 这是一笔拨款，旨在解决聚合物流变学研究中的许多重要问题，这些问题可以被表征为非连续体或非局部。 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。 人们对这些问题的兴趣日益浓厚，源于对分子水平材料加工的需求不断增长。 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，例如沿着分子主链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，这些高度受限的流场现在才刚刚开始受到实验质疑，但早期数据表明，在这些情况下需要理解新的神学行为。选择了可以作为理论模型构建范例的三个问题进行研究：a）当孔或通道厚度与聚合物的回转半径相当时，溶液中柔性链的库埃特-泊肃叶流动，b）聚合物溶液在边界附近的整体剪切流，其中界面可能包含吸附或接枝的聚合物层，以及c)“湿”聚合物刷覆盖表面的挤压流润滑。 将使用的技术是一种新颖的混合方案，涉及使用HP自适应有限元的自洽流动计算和珠杆（克莱默）链的大规模布朗动力学模拟。