CAREER:SusChEM: Design and Discovery of Polymers with Pendant Rings for Membrane Gas Separations

由于操作简单、结构紧凑、模块化和高能效，膜技术已成为一种重要的气体分离技术。然而，用于诸如CO2/CH4和C3H6/C3H8分离等重要应用的膜，当制成工业薄膜在CO2和重碳氢化合物的强塑化成分存在下工作时，其分离性能会受到限制。这些聚合物在20微米或更厚的薄膜中可能具有优越的纯气体分离性能。然而，在工业复合膜的~100 nm薄膜中，这些聚合物的透气性随着时间的推移而迅速下降（即老化）。二氧化碳和碳氢化合物使聚合物基体膨胀（即塑化），导致颗粒筛选能力减弱，气体选择性降低。该项目将通过对聚合物结构与薄膜性能（包括渗透性、选择性、老化和塑化）之间关系的分子机制理解来解决这些问题。综合教育活动预计将实现以下效益：(a)为布法罗公立学校（该地区大部分学生的背景在STEM领域代表性不足）的初中和高中教师和学生提供膜技术解决全球气候变化的教育模块；(b)正在进行的聚合物讲习班，以促进布法罗校园和纽约西部地区的跨学科合作；(c)改进传热传质和材料表征的核心课程，以激励学生？对膜研究感兴趣；(d)为本科生和研究生提供高分子合成、表征、膜分离和建模方面的跨学科培训机会。该研究项目将阐明高分子材料中聚合物垂环和交联对膜气体分离性能的影响，包括透气性和选择性、薄膜抗老化稳定性和抗烃致塑化稳定性。这些庞大的悬垂环破坏了聚合物链的填料，导致高自由体积和渗透性，它们还有望减缓聚合物链的运动，减少致密化或物理老化。在化学合成过程中可以方便地调整环的大小，并引入取代基来合理设计结构。将产生自下而上的交联网络设计，预期具有抗塑化能力。采用一种改进的自由体积模型来阐明老化和塑化对膜分离性能的影响。这个跨学科的研究项目集材料的发现、合成、表征、建模和应用于一体，将丰富对膜气体分离中聚合物结构/性能相关性的基本理解。预计从该项目中获得的技术方法和材料设计准则将直接应用于节能气体分离工业膜的开发。这个职业项目也有望提高学生的？具有设计和发现材料以解决重要实际问题的意识。

CAREER 1554236-LinMembrane technology has emerged as an important gas separation technology due to simplicity of operation, compactness, modularity, and high energy efficiency. However, the available membranes for important applications such as CO2/CH4 and C3H6/C3H8 separations are restricted by their deteriorated separation performance when made into industrial thin films operating in the presence of strongly plasticizing components of CO2 and heavy hydrocarbons. These polymers may have superior pure-gas separation performance in thick films of 20 µm or more. However, in the thin films of ~100 nm for industrial composite membranes, these polymers show gas permeability rapidly decreasing with time (i.e., aging). The CO2 and hydrocarbons swell the polymer matrix (i.e., plasticization), leading to weaker size sieving ability and reduced gas selectivity. This project will address these issues by developing a molecular-based mechanistic understanding of the relationship between the polymer structure and thin film properties including permeability, selectivity, aging and plasticization. The integrated educational activities are expected to achieve the following benefits: (a) an educational module for teachers and their students in middle school and high school in the Buffalo Public Schools (a district with a large fraction of students whose background is underrepresented in STEM fields) on membrane technology to solve global climate change; (b) an ongoing polymer workshop to promote the interdisciplinary collaboration on the Buffalo campus and in the Western New York area; (c) improvement in the core courses of Heat and Mass Transfer and Materials Characterization to stimulate students? interests in membrane research; and (d) interdisciplinary training opportunities in polymer synthesis, characterization, membrane separation and modeling for students at the undergraduate and graduate level. The research project will elucidate the effect of polymer pendant rings and crosslinking in the advanced polymeric materials on membrane gas separation properties, including gas permeability and selectivity, thin film stability against aging, and stability against hydrocarbon induced plasticization. These bulky pendent rings disrupt the polymer chain packing, leading to high free volume and permeability, and they are also expected to slow the chain motion, reducing densification or physical aging. The size of the rings will be conveniently tuned during the chemical synthesis, and substituents will be introduced to rationally design the structure. A bottom-up design of crosslinking networks will be generated, which are expected to be resistant to plasticization. A modified free volume model will be used to elucidate the effect of aging and plasticization on membrane separation properties. This interdisciplinary research program integrating materials discovery, synthesis, characterization, modeling and applications will enrich the fundamental understanding of polymer structure/property correlation for membrane gas separation. It is anticipated that the technical approach and materials design guidelines derived from this project will be directly applied to the development of industrial membranes for energy-efficient gas separation. This CAREER project is also expected to enhance students? awareness of materials design and discovery to solve important practical problems.