Date of Award

Spring 2019

Degree Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

School

Polymer Science and Engineering

Committee Chair

James W. Rawlins

Committee Chair School

Polymer Science and Engineering

Committee Member 2

Sarah E. Morgan

Committee Member 2 School

Polymer Science and Engineering

Committee Member 3

Sergei I. Nazarenko

Committee Member 3 School

Polymer Science and Engineering

Committee Member 4

William L. Jarrett

Committee Member 4 School

Polymer Science and Engineering

Committee Member 5

Robson F. Storey

Committee Member 5 School

Polymer Science and Engineering

Abstract

There is an important and ongoing debate on how or whether conductive polymers (CP) alter corrosion performance with some researchers reporting that CPs ultimately accelerate corrosion and others saying CPs, if understood could possibly replace the world’s best standard for corrosion prevention, i.e., chromium based inhibitors. The primary project goal was to improve our understanding of how CPs alter corrosion chemistry by 1) controlling the polymer structure and 2) in-turn the properties and then 3) targeting the best protocol for fast corrosion kinetic evaluation.

We detail the copolymer synthesis results and shift in corrosion protection properties for a series of polythiophene copolymers with variation in solubility and measured onset oxidation potential. Controlled polymerization can be achieved, the properties were predictable based upon the resulting comonomer composition, and we explain how these properties affect corrosion kinetics. We confirm that the lower onset oxidation potential decreases corrosion rates over steel substrates, however performance peaks at an onset oxidation potential of 0.24 V vs Fc/Fc+. Further, we confirmed our hypothesis that CPs like polythiophenes affect corrosion primarily by a combination of differences in ion barrier properties and shifted anodic polarization of the substrate. Additionally, another hypothesis is further supported in that there is/was an optimal 3,4-ethylenedioxythiophene content for the polymer to achieve the best performance for steel.

The data presented here helps improve our understanding on how CP affect corrosion, the characteristic properties that are tunable for better CP design towards anti-corrosive primers, and how to adequately evaluate the material combinations performance.

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