Traditional approaches to synthesize surface initiated (SI) polymer brushes start with solvated monomer in contact with an initiator functionalized surface. This technique creates a monomer concentration gradient where the concentration of monomer is very low near the surface, resulting in SI brushes with limited thickness and significant polymer length dispersity. Inspired by the biological counterparts of SI brushes, our lab developed a “passing-through” technique to invert this gradient and increase the brush uniformity by supplying monomer from underneath the functionalized membrane. However, these brushes were limited to monomer-permeable membranes. Here we present a method where a swellable rubber substrate allows for the monomer to diffuse out of the substrate to give the same inverted monomer concentration gradient. In this case the rubber substrate is functionalized and then swollen with the monomer of choice. This monomer then slowly diffuses out of the substrate and polymerizes as it passes through the surface. However, because the substrate is swollen, the initiation sites are spread out, allowing for the growing brush to have little to no steric hindrance while it is growing, while also contracting during the polymerization process thus bringing the chains closer together. The brushes grown using this passing-through approach is shown to give a greater water contact angle, contain a greater mass of polymer brush, and form crystalline polymer brushes on the surface.

Passing-through surface-initiated polymerization on a rubber substrate: Supplying monomer from swollen substrates

ACS Spring Meeting 2021

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