Date of Award

Summer 6-2-2023

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Derek L. Patton

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Robson F. Storey

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Sarah E. Morgan

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Sergei Nazarenko

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

James W. Rawlins

Committee Member 5 School

Polymer Science and Engineering

Abstract

The overarching focus of my research is the use of graphene and graphene derivatives to enhance polymer properties. My first focus area was the prevention of oxidative degradation of asphalt through the incorporation of a graphene oxide (GO) -based nanoparticle filler to enhance oxygen barrier properties. Primary amine terminated polyisobutylene was synthesized via cationic polymerization followed by post polymerization chain end modification in a range of molecular weights and covalently grafted via the primary amine to graphene oxide aerogel (aGO) to create a polyisobutylene grafted graphene oxide (PIB-g-GO) nanoparticle. PIB-g-GO was then mixed into a substitute asphalt matrix at various loadings and oxygen barrier properties were evaluated in a MOCON apparatus where the best performing sample reduced oxygen permeation by 60.1% with a weight loading of 1%. This best performing sample was scaled up, incorporated into asphalt binder and artificially aged. FT-IR analysis of the aged material found oxidative aging occurred 5 times slower with PIB-g-GO incorporation and rheological testing found the high temperature performance was greatly enhanced. My second research focus was the incorporation of graphene into a dynamic polymer matrix to enhance the thermal conductivity of the resulting composite. First, a dynamic epoxy vitrimer was synthesized and characterized for vitrimeric properties including determination of dynamic bond activation energy, topological freezing temperature (Tv) and glass transition temperature (Tg). Then, graphene was incorporated into this novel epoxy vitrimer in a segregated dispersion at various weight loadings and the thermal properties of the resulting composites were evaluated below Tv and Tg, above Tv but below Tg and above both Tv and Tg to study the interfacial interactions between filler and matrix in these ranges of differing matrix mobility. Second, a thiourethane dynamic network was synthesized with dynamic trans-thiol carbamylation crosslinks and used to create a segregated conductive polymer composite (s-NCP). Network stoichiometry and reprocessing conditions were altered to study the effect on the morphology of the segregated filler and probe the structure property performance relationship in these novel s-NCPs with a dynamic matrix. Finally, a series of s-NCPs with filler loadings ranging from 0.05 – 2.19 vol% graphene was synthesized and the highest thermal conductivity achieved was 2.96 W M-1 K-1 with a filler content of 0.54 vol%.

Available for download on Monday, June 02, 2025

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