Mid-Segment Polydispersity as a New Tool for Manipulating ABA Triblock Copolymer Morphologies and Properties

具有不同寻常的化学功能和有用的物理性质组合的创新聚合物材料的发展对于其作为高强度结构材料，水和气体净化膜，有机光伏电池组件和大功率锂离子电池材料的无数应用至关重要。在一个高度跨学科的研究环境中，该项目将挑战本科生和研究生在化学、化学工程和材料科学之间的界面进行假设驱动的横切研究。通过使用合成聚合物化学中的现代方法来生成新材料，并通过表征其结构和随之而来的物理性质，该项目旨在发现新的工具来设计具有不同形态和新特性的创新功能聚合物，用于各种潜在应用。一个本科高分子化学实验室和两个以高分子为导向的讲座示范将用于一般化学教学和公共宣传讲座。商品和特种嵌段共聚物的应用依赖于它们有用的性能组合，这源于共价连接两个或多个不同的均聚物片段成单个大分子。由于其热力学驱动的自组装成复杂但定义良好的纳米级形态，嵌段共聚物可用于热塑性塑料和热塑性弹性体，先进的分子分离膜以及制造下一代微电子的新模板。现代聚合技术使我们能够获得大量的共聚物，这些共聚物含有不同寻常的化学功能组合和有用的物理性质，但代价是在共聚物的一个或多个块段中引入显著的片段分散性。然而，广泛的节段分散性对嵌段共聚物相行为的作用尚未得到很好的理解。本项目将直接研究中间段多分散性对aba型三嵌段共聚物相行为的影响。模型多分散三嵌段共聚物具有不同的段间相互作用参数将通过串联聚合技术合成，以研究其组成依赖的相行为，使用小角度x射线散射，电子显微镜，聚合物流变学和各种输运测量。在有序-无序过渡（ODT）附近表征样品将有助于确定参数化这些多组分嵌段共聚物混合物相行为的变量。最终，本研究旨在将片段多分散性转化为一种新的工具，用于操纵具有技术上有用的体性能的嵌段共聚物的形态。

NON-TECHNICAL SUMMARYThe development of innovative polymeric materials possessing unusual combinations of chemical functionalities and useful physical properties is crucial in their myriad applications as high-strength structural materials, water and gas purification membranes, components in organic photovoltaic cells, and materials for high power lithium-ion batteries. Within a highly interdisciplinary research environment, this project will challenge undergraduate and graduate students to conduct hypothesis-driven, crosscutting research at the interface between chemistry, chemical engineering, and materials science. By using modern methods in synthetic polymer chemistry to generate new materials and by characterizing their structures and attendant physical properties, this project will aim to uncover new tools for designing innovative, functional polymers with unusual morphologies and novel properties for a variety of potential applications. An undergraduate polymer chemistry lab and two polymer-oriented lecture demonstrations will be developed for use in general chemistry instruction and in public outreach lectures.TECHNICAL SUMMARYApplications of commodity and specialty block copolymers rely on their useful combinations of properties, which stem from covalently linking two or more dissimilar homopolymer segments into a single macromolecule. By virtue of their thermodynamically driven self-assembly into complex yet well-defined nanoscale morphologies, block copolymers are useful as thermoplastics and thermoplastic elastomers, advanced molecular separations membranes, and new templates for fabricating next-generation microelectronics. Modern polymerization techniques enable access to a plethora of copolymers containing unusual combinations of chemical functionalities with useful physical properties, at the expense of introducing significant segmental dispersity into one or more blocks of the copolymers. However, the role of broad segmental dispersity on block copolymer phase behavior is not well understood. This project will directly investigate the effects of mid-segment polydispersity on the phase behavior of ABA-type triblock copolymers. Model polydisperse triblock copolymers with varying segmental interaction parameters will be synthesized by tandem polymerization techniques for studies of their composition-dependent phase behavior, using small-angle X-ray scattering, electron microscopy, polymer rheology, and various transport measurements. Characterization of samples near the order-disorder transition (ODT) will help to identify the variables that parameterize the phase behavior of these multicomponent block copolymer mixtures. Ultimately this study aims to transform segmental polydispersity into a new tool for manipulating the morphologies of block copolymers with technologically useful bulk properties.