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.
