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

Career 1554236-Lin膜技术因操作简单、紧凑、模块化和高能效而成为一项重要的气体分离技术。然而，现有的用于CO2/CH4和C3H6/C3H8分离等重要应用的膜在制作成工业薄膜时受到分离性能恶化的限制，这些薄膜在二氧化碳和重烃的存在下具有强烈的增塑作用。这些聚合物在厚度为20微米或更厚的薄膜中可能具有优异的纯气体分离性能。然而，在用于工业复合膜的~100 nm薄膜中，这些聚合物的气体透过率随着时间的推移(即老化)而迅速下降。二氧化碳和碳氢化合物使聚合物基质膨胀(即增塑)，导致筛分能力减弱，气体选择性降低。该项目将通过发展基于分子的机制来了解聚合物结构与薄膜性能之间的关系，包括渗透性、选择性、老化和塑化，从而解决这些问题。综合教育活动预计将实现以下成果：(A)在布法罗公立学校(该地区有很大一部分学生的STEM背景在该领域的代表性不足)为中学和高中的教师和学生提供关于膜技术以解决全球气候变化的教育模块；(B)正在举办的聚合物讲习班，以促进布法罗校区和纽约西部地区的跨学科合作；(C)改进热质传递和材料表征的核心课程，以激励学生？(D)为本科生和研究生提供聚合物合成、表征、膜分离和建模方面的跨学科培训机会。该研究项目将阐明先进聚合物材料中的聚合物悬环和交联剂对膜气体分离性能的影响，包括气体渗透性和选择性、薄膜抗老化稳定性和抗烃诱导塑化稳定性。这些笨重的吊环扰乱了聚合物链的堆积，导致高自由体积和渗透率，它们还有望减缓链的运动，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。将产生一种自下而上的交联网设计，预计它将抵抗塑化。用一个修正的自由体积模型来解释老化和塑化对膜分离性能的影响。这一集材料发现、合成、表征、建模和应用于一体的跨学科研究项目将丰富膜气体分离中聚合物结构/性能关联的基础知识。预计该项目产生的技术方法和材料设计指南将直接应用于开发节能气体分离工业膜。这个职业项目也有望提升学生？具有材料设计和发现意识，能解决重要的实际问题。

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.