Laser‐Writing of Fluorescent Copolymers in Mesoporous Silica Thin Films

Abstract Local polymer grafting, as well as automated direct laser writing (DLW) of polymers in mesoporous films, is demonstrated. Especially when low polymer amounts are grafted at a very small scale, analysis of polymer functionalization is a challenge. DLW of fluorescent copolymer is presented in mesoporous silica with 12 nm mesopore diameter by a surface‐initiated photo electron/energy transfer‐reversible addition‐fragmentation chain‐transfer (PET‐RAFT) polymerization using a 405 nm laser of a commercially available microscope. By the copolymerization of fluorescent comonomers during DLW, fluorescent microscale patterns of copolymer of sulfopropyl acrylate (SPA) and fluorescein methacrylate (FLMA) are obtained. The polymer spot sizes, as well as the polymer amount, are precisely manipulated by adjusting the irradiation time or power. A method for the analysis of confocal fluorescence image data is introduced, allowing quantitative comparison of relative polymer amounts by the correlation of fluorescence intensities and polymer specific IR absorption intensities. In addition, profiles of spatial polymer distribution on the micrometer scale are deduced from fluorescence image data and investigated. The polymer spot analysis shows that polymer amount gradients within each micrometer sized polymer spot are precisely tuned using irradiation time and laser power.