Concerning Synthesis of New Biobased Polycarbonates with Curcumin in Replacement of Bisphenol A and Recycled Diphenyl Carbonate as Example of Circular Economy

Curcumin (CM) is a natural polyphenol wellknown for its antioxidant and pharmaceutical properties, that can represent a renewable alternative to bisphenol A (BPA) for the synthesis of biobased polycarbonates (PC). In the presented strategy, preparation of the CMbased PC was coupled with chemical recycling of the fossilbased BPA polycarbonate (BPAPC) conducting a twosteps transpolymerization that replaces BPA monomer with CM or its tetrahydrogenated colorless product (THCM). In the first step of synthetic strategy, depolymerization of commercial BPAPC was carried out with phenol as nucleophile, according to our previous procedure based on zinc derivatives and ionic liquids as catalysts, thus producing quantitatively diphenyl carbonate (DPC) e BPA. In the second step, DPC underwent a melt transesterification with CM or THCM monomers affording the corresponding biobased polycarbonates, CMPC and THCMPC, respectively. THCM was prepared by reducing natural bisphenol with cyclohexene as a hydrogen donor and characterized by H-NMR and MS techniques. Polymerization reactions were monitored by infrared spectroscopy and average molecular weights and dispersity of the two biobased polymers THCMPC and CMPC were determined by means of gel permeation chromatography (GPC). Optical properties of the prepared polymers were also measured.