Eco-Friendly polyester vitrimer: enhanced stretchability, self-healing, and reprocessability through dynamic covalent crosslinks via melt-polycondensation

Dynamic covalent polymer networks offer new possibilities for designing sustainable polyester vitrimers owing to their excellent reprocessability and malleability; however, maintaining the high performance of the adaptable network with amazing healing properties remains a challenge. Therefore, the proposed approach considers the one-pot synthetic strategy to fabricate highly stretchable polyester vitrimer networks via condensation polymerization of different aliphatic diacids such as glutaric acid, pimelic acid, azelaic acid with 1,4-butanediol in the presence of glycerol and dithiodicarboxylic acids as the curing agent and dynamic covalent crosslinkers. The synthesized polyester network with simultaneous disulfide metathesis and carboxylate transesterification exhibited vitrimeric behavior which can alter the topologies through the reversible bond exchange, displaying high elasticity, reprocessability, and self-healable properties. Gel fraction experiments, rheological studies, and self-welding ability demonstrated the dynamicity of the polyester network. Thermomechanical characteristics and vitrimeric features were analyzed by dynamic mechanical analysis, showing that stress relaxes very rapidly and has relaxation times ranging from 32 s to 210 s (at 170 °C) and 870 s to 2772 s (at 100 °C), while 100% self-healing efficiency was achieved when thermally triggered at 50^°C within 5 h. Moreover, the developed polyester vitrimer demonstrates extensive elongation (up to 2000%) properties depending on the dithiocrosslinker chain length, crosslink density, and excellent reprocessability. Even after reprocessing, the reprocessed vitrimers maintained almost the same mechanical characteristics and good reconfigurability, leveraging the dual bond-exchange mechanism. Briefly, the simplicity of the polycondensation process, application, and processing of this vitrimer can help direct the development of a new covalently adaptive elastomer with enhanced sustainability and performance.