Degree
Doctor of Philosophy (PhD)
Department
Chemistry
Document Type
Dissertation
Abstract
This work explores the role of positionally defined charges on the self-assembly behavior of a series of sequence-defined peptoid block copolymers. The unique ability to precisely control the number and position of each monomer unit along the polymer chain makes this system particularly well suited for uncovering how changes in monomer sequence alter the resulting structures. We employ a number of scattering techniques to uncover how systematically repositioning a single ionizable monomer, along an otherwise neutral polymer chain, alters the self-assembled micellar structures and subsequently their responsiveness to changes in their local environment.
Chapter 1 reviews previous efforts to transition the sequence-structure-function relationship exhibited in nature to synthetic systems to access tailorable structures.
Chapter 2 reports the determination of the intramicellar mass heterogeneity of the series of sequence-defined ionic peptoid block copolymers in dilute aqueous solution. Contrast variation small-angle neutron scattering analysis was used to determine how the position of the charged ionic monomer along the chain impacts the polymer chain packing and invasive water content throughout the micellar interior.
Chapter 3 expands upon the findings of Chapter 2 by investigating the effects of intermicellar interactions on the self-assembled aggregates. Semi-dilute solution contrast variation small-angle neutron scattering analysis was used to elucidate the effective interaction potential between neighboring micelles, along with the effects of these interactions on the internal structural details of the micellar aggregates. The dependence on ionic monomer position is also discussed.
In Chapter 4, micellar structural changes as an effect of extent of ionization were explored. A combination of small-angle neutron scattering and dynamic light scattering analysis was used to probe the micellar size changes as a function of both ionic monomer position and solution pH.
Chapter 5 reports the design and synthesis of a sulfonate containing submonomer, and its successful integration into sequence-defined peptoid chains via the solid-phase submonomer synthetic method. The designed submonomer is a strong acid structural analog of the weak acid installed along the chain for the previous chapters and expands the number of ionic monomers available for installation using this synthetic technique.
Date
10-25-2023
Recommended Citation
Barrett, Bailee N., "Sequence-Defined Ionic Peptoid Polymers: Synthesis, Characterization, and the Role of Charge Patterning" (2023). LSU Doctoral Dissertations. 6275.
https://repository.lsu.edu/gradschool_dissertations/6275
Committee Chair
Zhang, Donghui