CAREER: Engineering polymers cohesive energy density and free volume for highly selective organic separations

全球约10%的能源消耗（每人每年7.5吉焦）用于化学分离。提高工业分离的能源效率对降低成本和控制环境污染至关重要。溶质通常是从有机溶剂中分离出来的，在有机溶剂中，溶质是通过能量密集型的分离，如蒸馏和吸收来合成的。聚合物膜可以替代或与传统技术结合使用，根据它们通过膜材料的渗透性来分离物种。然而，为了使膜基分离在经济上具有竞争力，迫切需要新的方法来控制聚合物膜的选择性和寿命。该项目将开发一种通过作用于膜材料特性（内聚能密度）和形态（自由体积结构）来设计选择性的新方法。设计具有高内聚能密度的材料有望增强膜分离基于不同溶解度的分子的能力，而结合提供更均匀和永久自由体积的官能团有望增强基于其大小分离分子的能力。高内聚能密度和适当的自由体积结构的结合将产生聚合物膜，表现出以前无法实现的有机分离选择性。这个CAREER项目将结合实验和计算方法，通过混合商业和新型聚合物来发现一类新的材料。这些混合聚合物将被明智地选择，以显示高内聚能密度，并具有具有不可折叠自由体积结构的多孔网络。这些材料的结构将被系统地调整，以最大限度地提高目标物种的选择性，同时保证优越的长期稳定性。同样重要的是，这个CAREER项目将促进高中生、本科生、研究生、他们的家庭和公众的发现式学习。该项目的成果将通过讲习班和高中教育单元直接在课堂上传播，以提高公众的科学和工程素养，并通过有影响力的会议演讲和科学期刊上的出版物传播。在聚合物膜中定制选择性的传统方法通常是无效的。本项目的科学目标是发现、合成和理解用于有机溶剂反渗透和纳滤的下一代聚合物膜。内聚能密度和构型自由体积的左基序将在这些具有增强长期稳定性的高选择性膜的设计中得到利用。其基本假设是聚合物膜的溶解度选择性随着内聚能密度的增加而增加，而扩散选择性通过加入具有不可折叠构型自由体积的二甲基而系统地增加。利用实验和理论相结合的方法来测试这些假设，该项目将导致用于有机分离的高选择性和稳定的聚合物膜，并将丰富对基于膜的有机分离的结构-性能相关性的基本理解。这个跨学科的研究项目将利用材料的发现、合成、表征和建模作为一种工具，在不同的层次上教育不同的学生群体，提高公众的科学和工程素养。研究和教育将通过以下方式整合：i)为诺曼，OK地区的初中和高中学生提供教育模块；ii)美国西南地区的高级聚合物研讨会；iii)为俄克拉何马大学的化学工程专业学生提供新课程；iv)为不同的研究生，本科生和初中/高中学生提供跨学科培训机会。该奖项反映了美国国家科学基金会的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

About 10% of global energy consumption (7.5 GJ per person every year) is devoted to chemical separations. Enhancing the energy efficiency of industrial separations is crucial to decrease costs and control environmental pollution. Solutes are typically separated from the organic solvents in which they were synthesized using energy intensive separations such as distillation and absorption. Polymer membranes can be used in substitution of or in conjunction with traditional technologies to separate species based on their permeability through the membrane material. However, new methods for controlling the selectivity and lifetime of polymer membranes are urgently needed to make membrane-based separations economically competitive. This project will develop a new approach to engineer selectivity by acting on the membrane material properties (cohesive energy density) and morphology (free volume architecture). Designing materials that exhibit high cohesive energy density is expected to enhance the capability of a membrane to separate molecules based on their different solubilities, and incorporating functional groups that provide a more uniform and permanent free volume is expected to enhance the ability to separate molecules based on their size. The combination of high cohesive energy density and proper free volume architecture will yield polymer membranes exhibiting previously unattainable selectivity for organic separations. This CAREER project will combine experimental and computational approaches to discover a new class of materials prepared by blending commercial and novel polymers. These blended polymers will be judiciously selected to exhibit high cohesive energy density and have porous networks exhibiting non-collapsible free volume architecture. The structure of these materials will be systematically tuned to maximize the selectivity for target species while guaranteeing superior long-term stability. Equally important, this CAREER project will promote discovery-based learning for high school, undergraduate, graduate students, their families, and the general public. Results from this project will be disseminated directly in the classroom, through workshops and high-school educational modules to enhance public science and engineering literacy, and via influential conference talks and publications in scientific journals.Conventional approaches to tailor selectivity in polymer membranes are often ineffective. The scientific goal of this CAREER project is to discover, synthesize, and understand next-generation polymer membranes for organic solvent reverse osmosis and nanofiltration. The leit motif of cohesive energy density and configurational free volume will be leveraged in the design of these high selectivity membranes with enhanced long-term stability. The fundamental hypothesis is that a polymer membrane's solubility-selectivity concomitantly increases with increasing cohesive energy density, and that diffusivity-selectivity systematically increases via the incorporation of iptycene moieties that confer non-collapsible configurational free volume. Using a combined experimental and theoretical approach to test these hypotheses, this project will lead to highly selective and stable polymer membranes for organic separations and will enrich the fundamental understanding of structure-property correlations for membrane-based organic separations. This interdisciplinary research program will exploit materials discovery, synthesis, characterization, and modeling as a vehicle to educate diverse student populations at various levels and enhance science and engineering literacy among the general public. Research and education will be integrated via i) an educational module for middle and high school students in the Norman, OK area, ii) an Advanced Polymers Workshop in the Southwest region of the US, iii) a new course offering for chemical engineering students at the University of Oklahoma, and iv) interdisciplinary training opportunities for a population of diverse graduate, undergraduate and middle/high school students.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.