The molecular structure at the surface of polymer materials regulates physical and chemical properties such as reactivity, wettability, adhesion, friction, and biocompatibility. In recent years, bottlebrush polymers have gained attention in polymer research due to the ability to tune their unique architecture and functionality by tuning side chain length and composition. Bottlebrush polymers are comprised of numerous polymeric side chains densely grafted to a polymer backbone, the highly branched structure results in a steric repulsion between neighboring polymer sidechains, forcing these macromolecules to adopt a chain-extended conformation. While aspects of these polymeric structures can be characterized using standard approaches, the surface functionality and structure remain poorly understood due in part to challenges in selectively probing the interfacial layer. In this work we employ a unique combination of precision synthesis, molecular dynamics simulations, and surface specific nonlinear spectroscopy to elucidate the structure−property relationship of bottlebrush polymer surfaces. Using vibrational sum frequency generation spectroscopy (SFG), which is exquisitely sensitive to interfacial ordering and local symmetry and chemical compositions, we provide new insight into the surface structure of a recently synthesized fluorinated bottlebrush polymer based on poly(2,2,2-trifluoroethyl methacrylate). SFG measurements reveal a unique molecular structure at the surface that connects the surface composition and ordering of specific functional groups with the hydrophobicity. Changes in chain length for both bottle brush and linear analogs show a change in surface structure that is in agreement with coarse grained molecular dynamics simulations. This insight into the surface composition and structure is expected to drive new advances for future applications.

Probing the surface structure of fluorinated bottlebrush polymers with vibrational sum frequency generation spectroscopy and molecular dynamics simulations

2019 Spring National Meeting

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.