Bottlebrush polymer is a kind of macromolecule with dense side-chain densely grafted side-chains. Because of the steric force among the side-chains, bottlebrush polymer exhibits distinct behaviors. In addition, its complex structure offers additional dimensions to tailor bottlebrush polymer, which provides a platform to design bottlebrush polymer for different applications such as antifouling, drug delivery, photonic crystals.
This dissertation focuses on applying bottlebrush polymers for surface modification. Surface property is crucial for material applications. For this dissertation, we propose two different approaches to modify the surface properties by either applying a bottlebrush polymer coating layer on the surface or blending bottlebrush polymer additives with bulk materials. For chapter two, we report that bottlebrush polymers with an unsaturated polynorbornene backbone and thiol-terminated side chains can be cross-linked on demand by UV irradiation to produce uniform and insoluble bottlebrush polymer coatings. By comparing a parameter as normalized residual thickness, we systematically study the influence of UV dose, side-chain length, backbone DP, different chemical composition and temperature. The cross-linking process outlined in this work is simple, general, and efficient and produces solvent-resistant coatings that preserve the unique properties and functions of bottlebrush polymers. For the next chapter, we discuss another surface modification approach as utilizing bottlebrush polymer additives. Bottlebrush copolymer with poly(methyl methacrylate) (PMMA) and polystyrene (PS) mixed arm side-chains (BBPS-m-PMMA) is blended with either linear PS or PMMA before and after thermal annealing. We find that the bottlebrush copolymers segregated to air and substrate interfaces above a critical molecular weight of the linear homopolymer, consistent with an entropic preference for chain ends and shorter chains toward the interfaces. This segregation is used to tailor the surface wettability of blend films using bottlebrush additives as a minority component. Chapter four investigates the influence of polymer architecture on its phase distribution behaviors. We synthesize two different bottlebrush polymers with similar chemical composition but different architectures, i.e. bottlebrush copolymer with either random side-chains (BBPS-r-PMMA) or mixed arm side-chains (BBPS-m-PMMA). After blending them with linear homopolymers, different phase behaviors are observed. It is due to the miscibility differences caused by the architecture variations. Next, another bottlebrush polymer, bottlebrush poly(cyclohexyl methacrylate) (BBPCHMA) with linear PS is studied. PS and PCHMA has attractive chemical interactions, indicating a preference of mixing for the two different components. We find the truly segregation of bottlebrush copolymer is not only affected by  parameter and entropy effect, but also the surface energy, kinetical effects. Besides, the self-healing properties by the bottlebrush additives diffusion is demonstrated. In the sixth chapter, we study the chemical composition influence on bottlebrush polymer phase behaviors. Bottlebrush polymers with PS and polyethylene glycol (PEG) mixed arm side-chains (BBPS-m-PEG) are synthesized and blended with both PS linear polymers. Uniform phase can still be observed though the repulsive interaction between these two arms is relatively high. Entropy driven force overwhelms the preferences of lower surface energy composition at the interfaces and leads to the enrichment of additives with both compositions above a critical molecular weight of the linear homopolymer.