Date of Award

12-2025

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

Zhe Qiang

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Derek Patton

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Sergei Nazarenko

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

Xiaodan Gu

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Graham Collier

Committee Member 5 School

Polymer Science and Engineering

Abstract

Polyolefins (POs), particularly polyethylene (PE) and polypropylene (PP), are among the most widely utilized polymers globally, valued for their low production costs and favorable mechanical properties stemming from their semicrystalline microstructure. However, their extensive use and improper disposal have raised serious environmental and human health concerns. In response, PO-derived covalent adaptable networks (CANs) have emerged, integrating dynamic chemistries to enable recyclability and sustainable end-of-life strategies. While existing literature has largely focused on novel CAN systems, structure–property relationships, and network rearrangement in relation to thermal transitions (e.g., topological freezing temperature), the influence of network formation on crystallinity and crystallization kinetics remains underexplored. My dissertation addresses this gap by investigating how transesterification catalysts affect network formation and crystallinity in PE-based vitrimer systems. The first study examines the role of zinc(II) stearate (ZnSt) and 1,5,7-Triazabicyclo[4.4.0]dec-5-ene (TBD) on the non-isothermal crystallization kinetics of a PE-based vitrimer crosslinked with digylcidyl ether bisphenol A (DGEBA). Both catalysts act as nucleating agents, inducing distinct nucleation- and growth-dominated regimes depending on cooling rates. The second chapter expands this analysis to additional catalysts including zinc(II) acetylacetonate (Zn(acac)2), zinc(II) acetate (Zn(ac)2), and manganese(II) acetate (Mn(ac)2) and explores the effects of catalyst loading. Zn(acac)2, Zn(ac)2, and Mn(ac)2 promote higher gel fractions and strong nucleation abilities, though often at the expense of crystallinity. In contrast, ZnSt yields more moderate gel fractions, enabling enhanced crystallinity and mechanical performance, likely due to the more moderate gel content with thinner lamellae. All catalysts consistently exhibited dual crystallization regimes based on cooling rate. Additionally, I co-developed a Förster resonance energy transfer (FRET)-based method coupled with reversible addition–fragmentation chain-transfer (RAFT) polymerization to directly measure end-to-end distances and degrees of polymerization of oligomer chains in crude reaction mixtures. This approach successfully characterized chain conformation for polymerizations with styrene, methyl methacrylate, and methyl acrylate. The final chapters highlight outreach initiatives aimed at educating middle schoolers, college students, and the general public on sustainable materials research and recycling efforts, emphasizing the multi-faceted approach necessary to help solve the plastic waste problem.

ORCID ID

0009-0009-5050-0074

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