Application of photoredox catalysis in spatially controlled synthesis of conductive polymers

• Applicant: Professorin Dr. Olga Garcia Mancheno
• Subject Area: Preparatory and Physical Chemistry of Polymers ; Synthesis and Properties of Functional Materials ; Organic Molecular Chemistry - Synthesis and Characterisation
• Term: since 2024
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 544807608

This project aims to develop new photoredox-mediated polymerization approaches for the access to conductive polymers. Conductive polymers show broad electrical properties ranging from semiconductor behaviour to conductivities that are almost as high as for metals. Those properties make them perfect materials for portable or wearable electronic devices. They could be applied in elastic electronics, i.e., foldable smartphones or soft electronics for medical applications. Despite the huge demand for such devices, the use of conductive polymers in this area is limited by the difficult processing of such polymers. Therefore, they are mostly applied in form of composites with elastic hydrogels. Due to that, the development of new methods for the conductive polymer synthesis with spatial control over their structure is highly demanded. Application of light to initiate polymerization will enable their deposition in form of patterns or even micropatterns to prepare organic electronic circuits. Moreover, it would open possibilities to 3D-print conductive polymer structures. However, there are only a few reports regarding photopolymerization of conductive polymers. Moreover, reported approaches suffer from numerous drawbacks, including the use of harmful UV light or very high amounts of photosensitizers that can contaminate the obtained polymers. Our proposed strategy to solve some of the current issues relies on the excellent oxidation properties of visible light excited photoredox catalysts such as acridinium salts. The excited catalyst is capable to oxidize monomers such as pyrrole, thiophene and carbazole derivatives into their corresponding cation-radicals, which will then undergo polycondensation. We assume that this approach will allow us to obtain additional spatial control over the polymerization process and the structure of the obtained polymers. This means that if the photocatalyst would be regenerated by electrooxidation, the polymerization process would take place in close vicinity of the electrode surface resulting in deposition of very thin polymer films. Applying additional masks would result in illuminating only chosen parts of electrode surface and thus deposition of polymer films in form of patterns, i.e., dots or stripes is possible. Moreover, immobilization of the photocatalysts on the surface of nanoparticles (NPs) or using fluorescent NPs should result in deposition of conductive polymers in form of thin shells over these NPs. The conductivity, optical properties and possible applications of the obtained polymers in selective sensing will be investigated. In particular, we will imprint the synthetized polymers with (R)-β-hydroxybutyric acid and glipizide as model analytes and apply the obtained molecularly imprinted polymers (MIPs) in selective sensing of these compounds. In this regard, the mild nature of photocatalysis will allow a broader molecule compatibility and functional group tolerance.

• DFG Programme: Research Grants
• International Connection: Poland
• Cooperation Partner: Dr. Maciej Cieplak