Date of Award

Spring 5-7-2021

Level of Access Assigned by Author

Open-Access Thesis

Degree Name

Doctor of Philosophy (PhD)

Department

Chemistry

Advisor

William M. Gramlich

Second Committee Member

Alice E. Bruce

Third Committee Member

Carl P. Tripp

Additional Committee Members

Matthew Brichacek

Caitlin Howell

Abstract

Biofouling which is an accumulation of small species on submerged surfaces that causes detrimental impacts on economic and environmental factors for aquaculture activities and human health. To suppress the fouling, polymeric coatings from amphiphilic block copolymers provide nanostructured surfaces and carry multiple functional groups in a molecular chain. Polymers with quaternary ammonium functional groups enable material coatings to inhibit microbial adhesion by killing bacteria, consequently prolonging the material efficiency of, for example, medical implanted devices. Herein, well-defined architectures with full-arm density of quaternary ammonium bottlebrush polymers were generated from grafting-through ring opening metathesis polymerization (ROMP). Factors such as the halide counter ions, the molecular weight of MMs, and the pendent alkyl groups were scrutinized to understand how they affected ROMP kinetics. As a result, halide-ligand exchange between halide counter ions and Grubbs catalyst occurred and the polymerization deviated from pseudo first-order kinetics, but still followed controlled polymerization with desired molecular weight and dispersity below 1.30. Larger MMs and pendent alkyl groups reduced the ROMP propagation rates due to steric hindrance between the growing chains and incoming MMs. Next, a library of amphiphilic BBCPs were synthesized by sequential polymerization of polystyrene MMs (PS) and quaternary ammonium MMs to afford controlled macromolecular brush copolymers. To study phase separated morphologies of thin films corresponding to each block composition analyzed by atomic force microscopy (AFM), the desired BBCPs had volume fraction of PS and cationic domain as 25:75 and 50:50, respectively. As a result, AFM images showed morphological changes corresponding to different block compositions and side chain length symmetry. Additionally, morphology stability was investigated upon water submersion. The polymer films with 50:50 volume fraction demonstrated the morphology stability after water submersion for 3 days. The results of phase separated morphologies of the BBCP films are beneficial to create a promising amphiphilic coating that possess antimicrobial absorption on the surfaces. However, the study of antimicrobial performance of the BBCP thin films has not conducted yet.

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