SI‐bioATRP in Mesoporous Silica for Size‐Exclusion Driven Local Polymer Placement

Abstract Controlling the size‐exclusion driven localized placement of polymer chains within nanopores is essential for improving nanopore performance and bridging the gap between artificial and biological pores. While surface‐initiated reversible‐deactivation radical polymerizations are successfully employed for polymerization within nanopores, achieving simultaneous spatial control over polymer placement and minimizing catalyst usage remains a challenge. The study presents an example of enzyme‐catalyzed surface‐initiated atom transfer radical polymerization (SI‐bioATRP) conducted within mesoporous particles requiring only minimal catalyst amounts. It is demonstrated that the mesostructure of the host material can be utilized to guide the polymer placement. Hemoglobin serves as the catalyst for the polymerization of the negatively charged monomer potassium 3‐sulfopropyl methacrylate (KSPMA). The amount of grafted polymer is controlled by adjusting the density of silanol groups and the diameter of the mesopores. By employing mesoporous particles with pore neck diameters of 3.7 nm, polymer growth is predominantly restricted to the outer surface of the particles due to restricted accessibility of the catalyst and small molecules toward the mesoporous structure after initiator grafting, an effect confirmed by confocal laser scanning microscopy (CLSM). This work highlights the potential of SI‐bioATRP for polymer grafting and the size‐exclusion driven local polymer formation in mesoporous particles.