A Novel Approach for the Synthesis of Thermo-Responsive Co-Polyesters Incorporating Reversible Diels–Alder Adducts

The proof of concept for a new copolymerization approach taking advantage of the thermally reversible aptitude of the furan/maleimide Diels–Alder (DA) adducts is reported here. A new monomer bearing two carboxylic acids as end-groups and a Diels–Alder adduct within its structure is synthesized using benign and mild reaction conditions. Two polyesters are then fabricated from the DA-diacid and 1,6-hexanediol and 1,4-benzenedimethanol, respectively, and characterized by 1H-NMR, GPC, DSC, and TGA. Kinetic studies of these polyesters, performed by 1H-NMR spectroscopy at variable temperatures, establish the appropriate conditions for their controlled depolymerization, through the retro Diels–Alder reaction (rDA), and their re-construction through the DA reaction, showing moreover the reproducibility of this rDA/DA cycle. Finally, by exploiting this peculiar feature, a copolyester is successfully synthesized from the concomitant treatment of the two homopolymers, demonstrating the effectiveness of the method. The present approach provides a new method for the fabrication of multicomponent copolymers based on the DA/rDA strategy that is extendable to a variety of other polycondensation materials, such as polyesters, polyamides, polyurethanes, and epoxies, allowing the establishment of a library of novel architectures through this one-pot approach.