Polymer brush functionalization has become a powerful approach to tailor interfaces, often creating properties and behaviors that are inaccessible using analogous bulk materials. Their unique nature stems from versatility in polymer chain length, spacing, conformation, and chemical design. Brush-modified surfaces have led to great advances in surface and interface engineering, with their most well-known applications in the biomedical field, antibiofouling, functional nanomaterials and nanofabrication, wettability, colloidal stabilization, and other advanced technologies. As brush-modified technologies become more prevalent, accessible characterization of these interfaces and their response to changing experimental conditions is remains a challenge. Herein,we demonstrate the utility of silicon photonic microring resonators as a platform for the in-situ characterization of polymer brush surfaces. Microring surfaces were modified using surface-initiated atom transfer radical polymerization, enabling the construction of well-defined polymer brushes of hydrophilic, hydrophobic, and stimuli-responsive natures. Diffusion and partitioning of small molecules into the brushes were observed in real-time and conformation changes were quantified by measuring and fitting shifts in the resonance wavelength. In particular, this platform allows not only determination of solvent compatibilities based on small molecule partitioning depth, but also determination of partition and diffusion coefficients for small molecules in various polymer brushes. Additionally, polymer brush pKa can be extracted as a function of brush length and solvent conditions.Thus, we demonstrate that our technique allows for accessible characterization of diverse polymer layers in the presence of complex analyte-solvent interactions.

Real-time measurement of analyte partitioning and polymer brush conformation change

2019 Spring National Meeting

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