Date of Award

Fall 2020

Project Type

Dissertation

Program or Major

Chemistry

Degree Name

Doctor of Philosophy

First Advisor

Erik B Berda

Second Advisor

John G Tsavalas

Third Advisor

Marc A Boudreau

Abstract

Polymeric nanoparticles have been utilized in an increasing number of fields over the past two decades due to their unique properties such as design flexibility and good biocompatibility. Despite various techniques available to produce polymer nanoparticles, the preparation of small nanoparticles with customized functions in the sub 20 nm dimension remains challenging. Inspired by the self-organizing behavior of natural biomacromolecules, a class of single-chain nanoparticles (SCNP) are synthesized featuring biomimicry and ultrafine size. These nanoparticles are prepared from self-folding of polymer precursors bearing reactive pendant groups by intramolecular cross-linking reactions. A variety of cross-linking chemistries are available including covalent, dynamic covalent and non-covalent chemistries. Among these methods intramolecular polymerization is of particular importance as it allows for easy control of an SCNP’s degree of cross-linking, and lead to SCNP with tunable level of compaction.

The aim of this dissertation is to 1) provide a comprehensive overview of recent advances in the field of single-chain folding; 2) investigate the synthesis of SCNP by intramolecular polymerizations, and 3) study the synthetic variations relating to the efficiency of a polymer’s self-folding by intramolecular polymerization.

Chapter 2 of this work discusses the synthesis of poly(oxanorbornene imide) single-chain nanoparticles by intrachain radical polymerization of pendant methacryloyl units. Structure/ property relationships related to methacryloyl pendant length and percent incorporation were studied. Chapter 3 investigates the synthesis of an epoxide-maleimide bifunctional monomer, and its ring-opening polymerization to afford polyethyleneglycol based polymer precursor. The polymer precursor could undergo intramolecular radical polymerization to afford SCNP, and the cross-linked moiety could potentially be isolated for the study of degree of intrachain polymerization. Chapter 4 expands the scope of intrachain polymerization and explores the synthesis of SCNP by intramolecular ring-opening metathesis polymerization (ROMP). A series of poly(pentafluoro-methacrylate)s containing pendant norbornene imide groups was synthesized and subjected to intrachain ROMP. The efficiency of chain folding was explored relating to norbornene content on the polymer precursor, species and feed ratio of Grubbs catalysts, as well as doping effects of fluorinated aromatic comonomer.

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