Green synthesis of bio-based furan polyesters via ring opening polymerization

Polymers have quickly become indispensable to our society in packaging, smart materials, clothing, and electronics. In recent years, the development of bio-based and biodegradable polyesters (PEs) has become a promising sustainable alternative to crude-oil derived PEs. In particular, furan-based polyesters, such as poly(ethylene 2,5-furandicarboxylate) (PEF), are among the most extensively researched bio-baes polyesters. [1] However, despite their greener origin, the conventional synthesis of these polymers still involves harsh conditions and metal catalysts, leading to the production of undesired by-products that must be removed from the reaction mixture furthermore their recycling has been only marginally investigated. [2] Thus, critical aspects of advancing these greener materials are both improving their synthesis, but also addressing their recycling. A possible solution for the latter issue could be the Cyclo-DePolymerization (CDP), Ring-Opening Polymerization (ROP) approach. From these premises, our recent work has been focused on developing alternative synthesis to bio-based PEs via ROP of macrocycles prepared starting from furan-based monomers, such as 2,5-furandicarboxylic acid dimethyl ester (FDME). ROP methods are emerging as a valuable alternative, especially for renewable polymer synthesis. [3] The synthesis of macrocycles was carried out by reacting FDME with different diols such as tetraethylene glycol and hexaethylene glycol. Two synthetic approaches were investigated, pseudo-high dilution condensation [4] and (CDP). [5] Thus, ROP experiments were carried out on both the pure isolated macrocycles and their mixtures via enzymatic catalysis. Various reaction conditions for ROP, including catalyst/enzyme type, solvent, concentration, and temperature, were investigated. The structural characterization of the polymers obtained was carried out employing FTIR, NMR, TGA, GPC and DSC techniques.