Honeycomb structured porous films from a platinum porphyrin-grafted poly(styrene-co-4-vinylpyridine) copolymer as an optical oxygen sensor

The rational design and realization of revolutionary sensing films for improving the sensitivity and photo-stability of oxygen sensors have been long-standing challenges. We presented a facile approach for the fabrication of honeycomb structured porous films for optical oxygen sensors using a platinum porphyrin-grafted poly(styrene-co-4-vinylpyridine) (PtTFPP-PSVP) copolymer. Honeycomb porous films were prepared by the “Breath figure method”, which provides an efficient and cost-effective method to produce highly ordered honeycomb patterns in PtTFPP-PSVP copolymer films at sub-micrometer dimensions. Importantly, the application of these ordered honeycomb structured porous films as oxygen sensors afford exceptional improvement in sensitivity performance and exhibited 200% higher sensitivity than the solid sensing film owing to the higher accessibility of gas molecules and larger specific surface area. Furthermore, the photo-bleaching of sensor molecules for PtTFPP grafted to PSVP copolymer films could also be effectively alleviated and the sensors’ photo-stability was significantly improved compared with the physically incorporated PtTFPP into the same PSVP copolymer. Interestingly, the remarkably light intensity-changing characteristic of the sensing film under lower O₂ partial pressures facilitates convenient identification of O₂ concentrations even with the naked eye. We believe that the proposed honeycomb structured porous film could be a promising candidate in various oxygen sensing fields such as nearly anoxic systems, unsteady pressure measurements and unsteady flow visualization, etc. Additionally, the “Breath figure method”, owing to its simplicity, high reproducibility and easy processability, is expected to be readily applicable to a rich variety of other high performance gas sensor devices.