Date of Award

8-2019

Document Type

Dissertation

Degree Name

Doctor of Philosophy (PhD)

Department

School of Materials Science and Engineering

Committee Member

Igor Luzinov, Committee Chair

Committee Member

Philip J Brown

Committee Member

Olin Mefford

Committee Member

Olga Kuksenok

Abstract

For decades, water and oil repellency of engineering thermoplastics has been achieved with the introduction of long-chain perfluoroalkyl substances and moieties (CnF2n+1, n ≥ 7). However, their bioaccumulative and toxicological impact is now widely recognized and; consequently; the substances have been phased out of industrial production and applications. To this end, the key goal of this dissertation is to develop safe and effective replacements for the long-chain perfluoroalkyl substances.

Namely, we report here on synthesis, characterization, and application of perfluoropolyether-based copolymers as low surface energy oligomeric additives to engineering thermoplastics. First, perfluoropolyether-based triblock polyester copolymers with different end-groups were obtained via polycondensation polymerization. Then, the materials were blended with thermoplastic polymers, such as polyethylene terephthalate (PET), nylon 6, and poly(methyl methacrylate) (PMMA), at various concentrations to obtain oleophobic polymer films. The morphology and surface properties of the films were studied. The results show that the fluorinated triblock copolymers with non-fluorinated middle block readily migrate to the film boundary. They can form brush-like structure on the polymer film surface, and in doing so impart significant water and oil repellency to the polymer films.

The final part of this work was focused on synthesis and characterization of perfluoropolyether-based polyurethane materials (oligomers and block copolymer) obtained via step-growth polymerization. We found that the synthesis of the fluorinated polyurethanes is less challenging than the one for fluorinated polyesters. The wettability measurements indicated that addition of the polyurethanes to engineering thermoplastics offers somewhat higher water and oil repellency in comparison to the polyester based fluorinated block copolymers. However, the polyurethane materials have lower decomposition temperature.

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