Sustainable bisphenols for thio-catechol adhesives: Fundamentals of scalable oxidation, polymerization, and light-switchable mechanisms of adhesion & debonding

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The project focuses on the synthesis of nature-inspired TCC adhesives via thiol-quinone polyadditions, with an emphasis on the utilization of bioresources through the synergy of organic process development and material synthesis. The objectives of the planned investigations are twofold. On the side of organic method development (BUW, AK Kirsch), the focus will be on the investigation and establishment of a direct oxidation reaction of naturally occurring phenols to their corresponding quinones, while ensuring scalability and adherence to green principles. Since the standard reagent for this transformation, 2-iodoxybenzoic acid (IBX), is explosive in large quantities, the challenge is to develop batch and continuous catalytic processes for diphenol-bisquinone oxidation and to facilitate catalyst recyclability. On the side of material synthesis and polymer application (HUB, AK Börner), the study of sustainable bisquinones for the polymerization with multithiols is a key aspect, with the ultimate aim of enabling bio-based TCC-polymers suitable for adhesive applications. Using derivatives of the [2+2] photocyclization product of caffeic acid, TCC-polymer networks will be accessible and studied for their light-switchable cleavage and photoresponsive reorganization capability. These materials allow the exploration of highly demanded applications in the field of debonding and rebonding, but also the investigation of interesting concepts such as photostimulated healing of adhesion defects.