Functional Bottlebrush Polymer Additives for Thin Films and Coatings

Bottlebrush polymers are a class of highly branched polymers consisting of polymeric side chains that are densely grafted to a linear backbone. Their highly branched architecture results in surface enrichment across a broad range of materials. The goal of my research has been centered around the design of functional bottlebrush polymers and their use as surface active additives in blend films and coatings.

In the first chapter, we examine the segregation behavior of polystyrene bottlebrushes that are blended with linear polystyrene. We systematically vary the lengths of the bottlebrush backbone (Nb), side-chain (Nsc), and the linear matrix (Nm) in order to develop scaling laws, along with phase diagrams, that describe the segregation behaviors observed in thin films. Based on these results we established the design "rule" Nm/Nsc » 2 to aid in the development of a surface enriched bottlebrush/linear polymer system.

In the second chapter, we designed bottlebrush copolymers containing styrene (S) and the functional chemistry tert-butyl acrylate (tBA) as additives for polystyrene (PS) thin films. tBA is changed into acrylic acid (AA) by heating at moderate temperature, which allows for tuning of the adhesion and wettability of the film. Contact angle goniometry and immersion tests demonstrate the tuning of surface wettability and adhesion at the substrate, respectively, provided by the tBA/AA moieties.

In the third chapter, we synthesize bottlebrush-functionalized elastomers as fouling resistant coatings for use in marine environments. The bottlebrush polymer side-chains contained chemistries associated with anti-fouling and fouling-release properties. Coatings were prepared from each type of bottlebrush-functionalized elastomer, as well as binary and ternary blends thereof, on large-area panels. These panels were submerged in the Narragansett Bay (RI) and periodically observed over 4 months. We found that both hard and soft fouling varied across each coating, indicating that fouling resistance was controlled by both coating surface chemistry and topography.