Collaborative Research: Design a New Polymer Platform for Engineering Fast and Selective Molecular Transport in Membranes

聚合物基分离膜在许多技术创新中发挥着核心作用，如清洁能源（如H2净化）和环境修复（如碳捕获）。然而，膜领域发展的一个主要障碍是缺乏可行的合成方法来生产具有理想功能和组成的高分子量聚合物。在这个项目中，研究人员的目标是开发一种高度自适应的聚合物平台，以特定的大分子设计为目标，在聚合物膜中进行快速和选择性的分子运输。通过应用一种新的聚合工具和靶向特定结构基序来最大化分子运输，同时容易获得高分子量，本研究将为思考如何设计各种应用的聚合物膜材料开辟一个新的知识领域。此外，拟议的研究致力于教育和培训这一跨学科领域的各级学生，特别强调吸引代表性不足的学生进入聚合物材料研究。通过使用最近由首席研究员小组开发的Friedel-Crafts羟基烷基化聚合技术，该项目旨在合成一系列具有高分子量，在取代基和链结构上具有广泛可调性的三苯基甲烷骨架聚合物。聚合技术提供了一个机会，可以在不受分子量交叉影响的情况下，在多个长度尺度上探索聚合物结构（例如极性、位阻和形态）对气体输运性质的各自影响。研究人员假设，气体输运性质可能与取代基的变化有关，并会随着几何尺寸（对自由体积的物理影响）或极性（相互作用的化学效应）而变化。主要研究内容有：1)合成具有不同取代基的三苯甲烷基聚合物，研究不同取代基对气体输运的化学和物理影响；2)合成带有目标侧链的接枝三苯甲烷基聚合物，探讨中尺度形态对气体输运的影响；3)研究基本的气体传输特性（即渗透、扩散和吸附），并在理想和现实条件下评估膜的性能。该膜材料研究项目的最终目标是基于所提出的新型聚合物合成工具和聚合物平台所支持的严格的结构-性能关系确定，在聚合物中设计快速和选择性的气体输运。这里提出的合成衍生物将使研究人员能够分离化学和物理效应并独立研究它们。该项目由界面工程项目（工程理事会的化学、生物工程、环境和运输系统部门）和聚合物项目（数学和物理科学理事会的材料研究部门）共同支持。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。

Polymer-based separation membranes play central roles in many technological innovations, such as clean energy (e.g., H2 purification) and environmental remediation (e.g., carbon capture). However, one major barrier to advancement in membrane field is the lack of feasible synthetic methods that can produce high-molecular-weight polymers with desirable function and composition. In this project, the investigators aim to develop a highly adaptive polymer platform that targets specific macromolecular designs for fast and selective molecular transport in polymeric membranes. By applying a new polymerization tool and targeting specific structure motifs for maximizing molecular transport while readily achieving high molecular weights, this research will open a new intellectual area for thinking about how to design polymer membrane materials for a variety of applications. In addition, the proposed research is dedicated to educating and training students at all levels in this interdisciplinary field with particular emphasis to attract underrepresented students into polymer materials research. By using the Friedel-Crafts hydroxyalkylation polymerization technique recently developed in the principal investigator's group, the project aims to synthesize a series of triphenylmethane-backboned polymers that have high molecular weight, a wide range of tunability on both substituent groups, and chain architectures. The polymerization technique provides an opportunity to explore the respective effect of polymer structures (e.g., polar, steric and morphological) at multiple length scales on gas transport properties without cross-influence from molecular weight. The investigators hypothesize that gas transport properties can be correlated with variations in the substituent groups and will vary with geometric size (physical effects on free volume) or polarity (interactive chemical effects). Three major research tasks are planned: 1) to synthesize triphenylmethane-based polymers with various substituent groups to investigate the respective chemical and physical effects of functional groups on gas transport; 2) to synthesize graft triphenylmethane-based polymers with target side chains to interrogate the mesoscale morphological effect on gas transport; 3) to investigate fundamental gas transport properties (i.e., permeation, diffusion, and sorption) and evaluate membrane performance under both ideal and realistic conditions. The ultimate goal of this membrane materials research project is to engineer fast and selective gas transport in polymers based on the rigorous structure-property relationship determination enabled by the proposed new polymer synthesis tool and polymer platform. The synthetic derivatives proposed here will allow the investigators to decouple chemical and physical effects and study them independently. The project is supported by both the Interfacial Engineering program (Chemical, Bioengineering, Environmental, and Transport Systems Division of the Engineering Directorate) and the Polymers program (Division of Materials Research in the Mathematical and Physical Sciences Directorate).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.