Surface-Plasmon- and Green-Light-Induced Polymerization in Mesoporous Thin Silica Films.

The near-field of surface plasmon resonances at planar metal surfaces is confined to the nanoscale, but its resonance wavelength is located in the visible light range, making it interesting for confining polymer functionalization of surfaces but incompatible with the majority of polymerization reactions. Here, fluorescein as a polymerization initiator allowing dye-sensitized polymerization with green light (438-540 nm) is demonstrated to allow polymer functionalization of mesoporous films deposited onto planar silver metal layers. The fluorescein-induced polymer functionalization of mesoporous silica films is investigated with respect to the influence of irradiation power and irradiation time and its potential to generate polymer gradients. Finally, the polymer functionalization of mesoporous films upon surface-plasmon-initiated polymerization is demonstrated. Polymer functionalization thereby determines pH-responsive ionic mesopore accessibility. Consequently, these results present a sound basis for further nanoscale near-field-induced polymer functionalization of porous films.