Ring-opening (co)polymerization of cardanol glycidyl ether

The anionic ring-opening copolymerization of commercially available bio-based cardanol glycidyl ether (CGE) was investigated without any prior purification. As a first step, anionic-ring-opening homopolymerization was attempted through active chain-end and monomer-activated mechanisms. Both strategies were unsuccessful. Conversely, in a second step, the anionic alternating ring-opening copolymerization (AAROP) of CGE with the renewable N-acetyl homocysteine thiolactone (NHTL) was successfully carried out in the presence of a strong base. Anisole, a solvent classified as sustainable and rarely used in anionic ring-opening polymerization, proved to be a suitable for the AAROP. This polymerization is an unusual example of synthesis of linear polyesters with cardanol-based monomers. The copolymers were carefully characterized by 1H, 13C, COSY, HSQC, 1H-15N NMR and MALDI-ToF, demonstrating an alternating structure. Then, CGE was copolymerized with NHTL and another additional epoxide. The cardanol-derived monomers enable the preparation of functionalizable poly(ester-alt-thioether) bearing multiple allyl and alkene groups. The AAROP method in anisole offers new opportunity for green anionic polymerization through the use of sustainable chemicals, witnessed by the valorization of cardanol-derived compounds and expands the scope of synthesized renewable polyesters.