Surface-Initiated Passing-Through Polymerization on a Rubber Substrate: Supplying Monomer from Swollen Substrates

Passing-through polymerization is a technique for growing surface-initiated polymer brushes where monomers are supplied to the growing chains by diffusing through the initiator-functionalized surface. This inverts the monomer concentration gradient relative to conventional grafting-from mechanisms, allowing for the synthesis of thicker and more densely packed brushes. Here we use a combination of coarse-grained computer simulations and experimental techniques to demonstrate how this approach can be implemented, with swellable network-like substrates supplying monomers to the functionalized surface as they diffuse out of the swollen network. Compared to grafting-from polymer brushes, this method shows a higher contact angle and a greater brush mass. Additionally, we observed that the passing-through approach could lead to strain-induced crystallization in the brush layer or wrinkling of the brush surface, which we used to estimate the brush thickness. The developed method opens a path for large-scale synthesis of the brush-modified elastic substrates.