Date of Award

Spring 5-12-2022

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Dr. Xiaodan Gu

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Dr. Derek Patton

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Dr. Sarah Morgan

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Dr. Sergei Nazarenko

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Dr. Jeffery Wiggins

Committee Member 5 School

Polymer Science and Engineering

Abstract

Copolymers represent a broad, but critically important class of materials. Often having properties superior to either of its constituents, copolymers are used in virtually all industries including automotive, aerospace, coatings, packaging, and cosmetics. Certain copolymers microphase separate to form nanosized domains that improve the physical properties of the copolymer. The polymer community already has a thorough understanding of how phase separation occurs, but the commercialization of phase separating copolymers lags significantly behind academia. Many of the copolymers that exist that have been undercharacterized and underutilized. This dissertation examines two such polymers. The first, a hard polystyrene material with soft nanodomains. The second, a soft polypentenamer rubber with hard nanodomains. These copolymers have very different physical properties, and thus very different intended applications. The common thread connecting the works in this dissertation is an effort to harness microphase separation to enable new applications.

The first chapter gives an overview of copolymer architectures, properties, and their applications. Special attention is given to linear diblock copolymers as well as thermoplastic elastomers as these are most relevant to Chapters II-III and IV-V respectively. Chapter II explores the use of self-assembling diblock copolymers for use as ultrafiltration membranes. In this chapter a new membrane manufacturing process is described that quickly turns dense block copolymer films into porous membranes. Chapter III expands on this work by demonstrating a novel BCP annealing method that reduces domain size variation and is roll-to-roll printing compatible.

In Chapters IV and V, we shift gears from studying glassy diblock copolymers, to soft multiblock elastomers. Chapter IV explores the effect of incorporating a glassy monomer into a crosslinked elastomer in a search for a natural rubber replacement. It was found that modest glassy block incorporation could greatly increase tensile strength. Chapter V then clarifies the strengthening mechanism observed in Chapter IV by looking at the effect of the glassy monomer before chemically crosslinking the elastomer. This work showed that phase separation of the glassy domains created physical crosslinks demonstrating thermoplastic elastic behavior.

Finally, in Chapter VI some general conclusions about the research are recapped and put into a broader perspective. Suggestions for future work are then provided that would further the knowledge in both of the research directions.

ORCID ID

0000-0001-7469-8454

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