Doctor of Philosophy (PhD)
This work covers efforts to develop a peptoid-based model system for systematically studying the role of ionic functional groups in determining the structure of ionic block copolymer (BCP) self-assemblies in water. A key challenge in the study of polyelectrolytes is the lack of synthetic control over the location of ionic monomers along a polymer chain. We developed a model system based on sequence-defined ionic peptoid BCPs having discrete chain length and precisely positioned ionic monomers along the chain to specifically address this issue. In Chapter 1, synthetic strategies to access well-defined polypeptoids and their application in BCP synthesis are reviewed.
Chapter 2 covers the design of a library of sequence-defined ionic peptoid BCPs and the characterization of their self-assembly in aqueous media. The library of materials with discrete chain length and precisely positioned ionic monomers (one or three) along the peptoid chain were obtained by SPPS. By systematically varying the location of ionic monomers along the peptoid BCP chains, the effect of ionic group location on self-assembled micelles can be studied.
In chapter 3, the response of self-assemblies of sequence-defined peptoid BCPs having discrete chain length to varying pH is studied. The weakly acidic nature of the carboxylic acid group used in the design of the library of sequence-defined ionic peptoid BCPs gives rise to stimuli-responsive behavior as the solution pH is varied.
Chapter 4 covers the synthesis of an R-NCA monomer bearing N-2-carboxyethyl that mimics the ionic sidechain used in the above sequence-defined ionic peptoid BCPs. The availability of this new NCA monomer allows the sequence-defined ionic peptoid BCPs to be accessed by polymerization methods.
Sternhagen, Garrett Leigh, "Sequence-Defined Ionic Peptoid Block Copolymers: Synthesis and Solution Self-Assembly" (2019). LSU Doctoral Dissertations. 5039.