Development of Molecular Simulation Techniques for Probing Solvent Effects in Polymer Films during Solvent Vapor Annealing

该奖项支持计算和理论研究，以模拟由聚合物制成的薄膜的方法-具有重复分子单元的长链分子组装。聚合物广泛用于日常材料，如汽车零件、塑料杯和食品包装，以及高科技应用，如微电子和太阳能电池。聚合物基材料的性能可以通过调整组成分子单元的排列来优化给定的应用。这促使工业和研究实验室的材料科学家寻找能够精确控制聚合物材料分子排列的加工技术。其中一种处理技术是溶剂蒸气退火，将聚合物薄膜暴露在溶剂蒸气中，使溶剂分子与聚合物薄膜混合，从而改变聚合物-聚合物相互作用并导致特定的结果排列。这种方法使材料科学家能够获得以前不可能实现的聚合物排列，从而为创造下一代材料铺平了道路。尽管该技术的价值已被证明，但由于缺乏对该技术的基础知识，尚未建立优化的通用协议。在这个项目中，PI将开发模型和计算机模拟方法，以获得基本的理解，推进预测建模，并使溶剂蒸气退火成为一种通用，实用和可靠的方法，促进各种技术相关应用的聚合物工程，如燃料电池，光伏和纳米膜。她还将在本科教育方面投入大量精力，特别是在她的研究实验室以及在课堂上通过她的高分子科学与工程导论课程对本科生进行培训和指导。作为聚合物领域许多全国性会议的组织者，她计划邀请来自全国各地的领先女性计算软材料科学家，促进聚合物科学研究的传播，并激励下一代女性科学家和领导者。技术概述：溶剂蒸汽退火是一种越来越广泛使用的聚合物加工方法，其中溶剂在聚合物薄膜内的存在增强了聚合物的流动性，改变了有效的聚合物-聚合物和聚合物-表面相互作用，并驱动形态变化。通过溶剂蒸汽退火和最终的瞬时溶剂蒸发，可以捕获一些在平衡状态下看不到的技术上有用的形态。尽管这种加工技术的价值已被证明，特别是在嵌段共聚物薄膜中，但由于缺乏关于溶剂退火和溶剂蒸发过程中溶剂、衬底和聚合物之间复杂相互作用的基本知识，标准化或通用的协议尚未建立。这种知识的缺乏部分是由于a)在原位探测这些溶剂-聚合物相互作用和溶剂介导的聚合物-聚合物相互作用的实验技术的局限性，以及b)在大多数聚合物的计算研究中，溶剂被隐式处理或当被显式处理时，溶剂和聚合物在溶剂蒸气退火过程中的动力学没有被捕获。为了解决这种缺乏基本知识的问题，本项目的总体目标是开发新的计算方法来模拟聚合物薄膜中的溶剂蒸汽退火。计算研究将揭示聚合物薄膜中溶剂诱导的形态变化的热力学和动力学，并为使用溶剂蒸气退火来实现均聚物共混物和共轭聚合物基薄膜的目标形态提供通用指南。通过与实验数据的比较，这些计算技术将得到验证，并为溶剂化学和溶剂蒸汽退火条件的选择提供指导，以实现所需的目标溶剂诱导聚合物膜的效果。这种基本的理解对于溶剂气相沉积成为一种通用的、实用的和可靠的方法是有价值的，它有助于设计用于各种技术相关应用的聚合物和其他软材料薄膜，如光刻、燃料电池、光伏和纳米膜。在这个项目中开发的计算工具将提供给其他研究均聚物和共轭聚合物以外的系统，如聚合物纳米复合材料和嵌段共聚物。PI还致力于在教育和外展工作方面取得卓越成就。她将在本科教育方面投入大量精力，特别是在本科生为拟议工作做出贡献期间对他们进行培训和指导。与提议工作相关的结果和工具也将包括在她秋季为化学工程和材料科学专业的本科生和研究生讲授的聚合物科学与工程导论课程中。PI将继续她过去的广泛努力，招募和留住女学生，并指导她们在工业、大学和国家实验室担任领导角色。通过她作为各种全国性会议组织者的角色，PI旨在邀请来自全国各地的领先女性计算软材料科学家，促进优秀工作的传播，并为未来几代女性科学家和领导者提供激励。

NONTECHNICAL SUMMARYThis award supports computational and theoretical research to simulate a method to fabricate films made of polymers - long chain like molecular assemblies with repeating molecular units. Polymers are used universally in every-day materials, such as automobile parts, plastic cups, and food packaging, and in high technological applications, such as microelectronics and solar cells. The properties of polymer-based materials can be optimized for a given application by tuning the arrangement of constituent molecular units. This motivates materials scientists in industry and research labs to find processing techniques that will enable precise control over the molecular arrangement within the polymer materials. One such processing technique is solvent vapor annealing, where the polymer film is exposed to a solvent vapor so that the solvent molecules mix in with the polymer film which alters the polymer-polymer interactions and leads to a particular resulting arrangement. This method has allowed materials scientists to obtain polymer arrangements that have not been possible to achieve before, thus paving a pathway for creating next generation of materials. Despite the proven value of this technique, optimized universal protocols have not been established due to a lack of fundamental knowledge about this technique. In this project, the PI will develop models and computer simulation approaches to gain fundamental understanding, advance predictive modeling, and make solvent vapor annealing a universal, practical, and reliable method facilitating the engineering of polymers for various technologically relevant applications, such as fuel cells, photovoltaics, and nanomembranes. The PI will also dedicate significant effort to undergraduate education, specifically through training and mentoring of undergraduate students in her research lab as well as in the classroom through her Introduction to Polymer Science and Engineering course. In her role as organizer of many national conferences in the area of polymers she plans to invite leading women computational soft materials scientists from around the country, facilitating the dissemination of polymer science research, as well as serving to inspire future generation of women scientists and leaders.TECHNICAL SUMMARYSolvent vapor annealing is an increasingly utilized polymer processing method where the presence of solvent within the polymer film enhances the mobility of the polymers, alters the effective polymer-polymer and polymer-surface interactions, and drives morphological changes. Through solvent vapor annealing and eventual instantaneous solvent evaporation, some technologically useful morphologies that are not seen at equilibrium can be trapped. Despite the proven value of this processing technique, especially in block copolymer films, standardized or universal protocols have not been established due to a lack of fundamental knowledge regarding the complex interplay between solvents, substrate, and polymer(s) during solvent annealing and solvent evaporation. This lack of knowledge is due in part to a) the limitations in experimental techniques for probing these solvent-polymer interactions and solvent mediated polymer-polymer interactions in situ, and because b) in most computational studies of polymers the solvent is treated implicitly or when treated explicitly the solvent and polymer dynamics during solvent vapor annealing are not captured. To address this lack of fundamental knowing the overarching goal of this project is to develop new computational approaches to simulate solvent vapor annealing in polymer films. The computational research will uncover the thermodynamics and kinetics underlying solvent-induced morphology changes within polymer thin films and provide universal guidelines on the use of solvent vapor annealing to achieve target morphologies in homopolymer blends and conjugated polymer based films. Through comparison with data from experiments these computational techniques will be validated and provide guidance on the selection of solvent chemistries and solvent vapor annealing conditions for achieving desired target solvent-induced effects in the polymer film. Such a fundamental understanding will be valuable for solvent vapor deposition to become a universal, practical, and reliable method facilitating the design of polymer and other soft materials films used in various technologically relevant applications, such as lithography, fuel cells, photovoltaics, and nanomembranes. The computational tools developed in this project will be made available for others studying systems beyond homopolymer blends and conjugated polymers, such as polymer nanocomposites and block copolymers. The PI is also committed to achieving excellence in education and outreach efforts. She will dedicate significant effort to undergraduate education, specifically via training and mentoring of undergraduate students during their contributions towards the proposed work. The results and tools pertinent to the proposed work will also be included in an Introduction to Polymer Science and Engineering course that she teaches in the fall to undergraduates and graduate students from chemical engineering and materials science. The PI will continue her extensive past efforts to recruit and retain female students and mentor them to leadership roles in industry, universities, and national laboratories. Through her role as organizer of various national conference, the PI aims to invite leading women computational soft materials scientists from around the country, facilitating the dissemination of outstanding work, as well as serving to inspire future generations of women scientists and leaders.