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 GJ）用于化学分离。提高工业分离的能源效率是降低成本和控制环境污染的关键。通常使用能量密集型分离（例如蒸馏和吸收）将溶质从合成它们的有机溶剂中分离。聚合物膜可用于替代传统技术或与传统技术结合使用，以基于物质通过膜材料的渗透性来分离物质。然而，迫切需要用于控制聚合物膜的选择性和寿命的新方法，以使基于膜的分离具有经济竞争力。该项目将开发一种新的方法，通过对膜材料性能（内聚能密度）和形态（自由体积结构）的作用来设计选择性。设计表现出高内聚能密度的材料预期将增强膜基于分子的不同溶解度分离分子的能力，并且引入提供更均匀和永久自由体积的官能团预期将增强基于分子的尺寸分离分子的能力。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，其对有机分离表现出以前无法实现的选择性。这个CAREER项目将结合联合收割机的实验和计算方法，以发现一类新的材料，通过混合商业和新型聚合物制备。这些共混的聚合物将被明智地选择以表现出高的内聚能密度，并且具有表现出不可塌陷的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，以最大限度地提高对目标物质的选择性，同时保证上级长期稳定性。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基于发现的学习。该项目的成果将直接在课堂上传播，通过讲习班和高中教育模块，以提高公众的科学和工程素养，并通过有影响力的会议讲座和科学期刊上的出版物。这个CAREER项目的科学目标是发现，合成和理解下一代有机溶剂反渗透和纳滤聚合物膜。在设计这些具有增强的长期稳定性的高选择性膜时，将利用内聚能密度和构型自由体积的主题。基本假设是聚合物膜的溶解度-选择性伴随着内聚能密度的增加而增加，并且扩散性-选择性通过引入赋予非可塌陷构型自由体积的蝶烯部分而系统地增加。使用实验和理论相结合的方法来测试这些假设，该项目将导致高选择性和稳定的聚合物膜的有机分离，并将丰富膜为基础的有机分离的结构-性能相关性的基本理解。这个跨学科的研究计划将利用材料发现，合成，表征和建模作为一种工具，以教育不同层次的学生群体，并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）俄克拉荷马州诺曼地区初中和高中学生的教育模块，ii）美国西南地区的高级聚合物研讨会，iii）俄克拉荷马州大学为化学工程学生提供的新课程，iv）为不同研究生群体提供跨学科培训机会，该奖项反映了NSF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.