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Author ORCID Identifier

0000-0002-0726-5672

AccessType

Campus-Only Access for Five (5) Years

Document Type

dissertation

Degree Name

Doctor of Philosophy (PhD)

Degree Program

Chemical Engineering

Year Degree Awarded

2022

Month Degree Awarded

February

First Advisor

Dr. John Klier

Second Advisor

Dr. Jessica D. Schiffman

Subject Categories

Chemical Engineering | Polymer Science

Abstract

High wear environments, such as microelectronics, aviation, and biomedical devices require extremely durable polymer coatings. Chemically grafting the polymers to the substrate has been shown to increase coating durability, even on polymeric substrates (e.g. balloon catheter). The surface-initiated polymerization of methylidene malonates were studied to determine if methylidene malonates can enable in situ polymerization on polymer surfaces. Methylidene malonates, a class of 1,1 disubstituted alkenes, were selected because they are capable of anionic polymerization when initiated by weak nucleophiles (e.g., carboxylate salts) in the presence of air and water. The polymerization of diethyl methylidene malonate (DEMM) was studied on polymer substrates without initiators in the backbone (poly(ethylene), (LDPE)), with varying levels of initiator in the backbone (poly(ethylene-co-acrylic acid) at 3 and 10 wt%, treated with sodium hydroxide (pEAA-3-Na and pEAA-10-Na)), and with even weaker nucleophiles (poly(ethylene-co-acrylic acid) (pEAA-10)). Eleven characterization techniques were evaluated to measure the reaction and chain conformations of grafted pDEMM, including attenuated total reflectance Fourier transform infrared (ATR FTIR) spectroscopy, mass spectrometry and atomic force microscopy. The challenges and advantages of each technique are described, and preliminary results are reported for some of the techniques; ATR FTIR was predominantly used to semi-quantitively measure the degree of grafting. For the first time, grafted pDEMM was demonstrated on the substrates containing carboxylic acid and carboxylate salts. During polymerization, DEMM exhibited transport phenomena, which was studied by measuring the area of the reaction front over time and compared to a non-reactive control. The comparison indicated the transport is mediated by the polymerization. The area over time was linear at the beginning of the reaction (< 30 min), and the slope increased with increasing initiator for the base treated samples (between 0.01-0.03 cm2/min). A heat map was constructed from ATR FTIR spectra to demonstrate the relationships between grafting and transport: pEAA-10 and pEAA-10-Na samples exhibited different patterns of heterogeneous grafting, while pEAA-3-Na samples demonstrated homogenously grafted pDEMM. By understanding the transport and heterogeneity of grafted pDEMM, we can optimize the covalent attachment of methylidene malonate primers to increase the adhesion and durability of coatings.

DOI

https://doi.org/10.7275/27243434

Creative Commons License

Creative Commons Attribution 4.0 License
This work is licensed under a Creative Commons Attribution 4.0 License.

Available for download on Wednesday, February 01, 2023

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