Investigating the Structural Coupling of Main chain and Sidechain Packing in the Solution Structures of Amphiphilic Coil-Comb Block Copolymers with Crystallizable Sidechains

合成聚合物（俗称塑料）在我们的日常生活中有着广泛的重要应用。聚合物的性质是由它们的化学结构决定的，可以通过化学合成来定制。在美国国家科学基金会化学部大分子、超分子和纳米化学项目的支持下，路易斯安那州立大学张东辉教授设计并合成了一种名为多肽的聚合物。多肽在结构上与蛋白质的多肽非常相似。她的研究小组试图了解多肽是如何在溶液中形成特定形状和大小的非常小的物体的。这些知识可以为进一步开发对生物医学应用有用的功能材料（例如，药物递送载体）提供信息。该项目为各级研究生和本科生研究人员提供了一个跨学科的培训环境。开发与研究主题相关的新课程材料和拓展活动有助于使科学课程现代化，激发人们对化学的兴趣，提高公众对科学发现及其影响的认识。本项目主要研究具有可结晶侧链的两亲性、盘状梳状的多肽嵌段共聚物（BCP）。目的是了解这些共聚物在稀溶液中的分子结构和超分子组装之间的基本关系。据推测，高度极性的主链和疏水结晶侧链可以导致小长度尺度（亚纳米范围）的多肽嵌段共聚物的等级有序，这是传统方法难以获得的。基于多肽的bcp非常适合作为本研究的模型，因为它具有很强的主链和侧链的结构耦合性，极性主链和非极性侧链发生微相偏析的强烈倾向，以及在调整侧链和主链结构方面的合成通用性。考虑到多种聚合物具有或可以很容易地用正烷基侧链修饰以进行侧链结晶，本研究有望对具有分层有序和可逆热响应特性的BCP纳米结构的设计具有广泛的意义。

Synthetic polymers (commonly known as plastics) have a wide range of important applications in our daily life. The properties of polymers are governed by their chemical structures and can be tailored through chemical synthesis. With the support from the Macromolecular, Supramolecular and Nanochemistry Program of the NSF Division of Chemistry, Professor Donghui Zhang of the Louisiana State University designs and synthesizes a type of polymer called polypeptoids. Polypeptoids are structurally very similar to polypeptides of proteins. Her research group seeks to understand how polypeptoids organize themselves to form very small objects of certain shapes and sizes in solution. This knowledge can inform further development of functional materials that are useful for biomedical applications (e.g., drug delivery carriers). This project provides an interdisciplinary training environment for graduate and undergraduate student researchers at all levels. Development of new course materials and outreach activities that are connected to the research topic serve to modernize the scientific curriculum, stimulate interest in chemistry, and enhance public awareness of scientific discoveries and impact. This project focuses on studying amphiphilic, coil-comb shaped block copolymers (BCP) of polypeptoids that have crystallizable sidechains. The goal is to understand the fundamental relationship between the molecular structures and the supramolecular assemblies of these copolymers in dilute solution. It is hypothesized that a highly polar backbone and hydrophobic crystallizing sidechains can lead to hierarchical ordering of the polypeptoid block copolymers at small length scales (in the sub-nanometer range) that are difficult to access by conventional means. BCPs based on polypeptoids are uniquely suited as models for this study due to the strong structural coupling of the main chain and sidechain crystalline packing, the strong tendency of the polar main chains and non-polar sidechains to undergo microphase segregation and the synthetic versatility in tuning the sidechain and main chain structures. Considering the wide range of polymers that have or can be readily modified with n-alkyl sidechains to undergo sidechain crystallization, this study is expected to have broad implications on the design of BCP nanostructures with hierarchical ordering and reversible thermo-responsive characteristics.