Biobased and/or biodegradable polyesters From the elaboration to the end-of-life

Since the beginning of the 21st century, interest in polyesters has been driven by current environmental concerns. Indeed, some of them can be biosourced (totally or partially), i.e. synthesized from renewable resources derived from biomass, and also biodegradable. The polymer is considered biodegradable if it is capable of leading in fine, through combined chemical and biological processes, to a mixture of water and carbon dioxide in an aerobic environment (or methane in an anaerobic environment). At present, despite exceptional growth in biosourced plastics of the order of 20% per year, the plastics industry's dependence on fossil resources remains overwhelmingly preponderant, since around 99% of plastics are of petrochemical origin. Dependence on this single resource can have long-term economic, ecological and political consequences. Although opinions still differ on the kinetics of fossil resource depletion, there is no doubt that fossil resources are becoming progressively scarcer, and so the need to find alternatives through the use of renewable resources arises. At the same time, it seems essential to develop production technologies such as plant-based biorefineries, which have less environmental impact than petrochemical processes responsible for significant greenhouse gas emissions. As for the end-of-life of these plastics, which are the subject of countless attacks due to poor waste management and their negative impact on the terrestrial and marine environments and on ecosystems, we need to look at the ways in which polyesters can be re-used, through various strategies such as composting or recycling. The various recycling mechanisms include mechanical recycling, as traditionally used for polyethylene terephthalate (PET), but also emerging recycling routes for PET or polylactide (PLA), such as chemical or enzymatic recycling. The (bio)degradation of polyesters, particularly in different environments (freshwater, seawater, domestic or industrial compost, soil, etc.), is now well documented in the literature, which shows that the biodegradation behavior of polyesters is drastically modified according to their own physico-chemical characteristics (intrinsic factors), as well as according to the environments studied (extrinsic factors).

The study and development of new polymeric materials of renewable and/or biodegradable origin, such as polyesters, therefore represent a major scientific and environmental challenge for academic research, as well as for the chemical and plastics industries. Polyesters are a fascinating family of polymers insofar as their end-of-life scenarios are very advantageous, since they can be processed by recycling (mechanical, chemical and even enzymatic) or biodegraded (in industrial or domestic composting, or even in the natural environment if necessary),...