Chemical recycling of polylactide waste by microwave assisted alcoholysis and hydrolysis

Polylactide (PLA) is an aliphatic polyester obtained from renewable resources, offering an attractive alternative to traditional petroleum-based plastics. Biocompatible, biodegradable, and with excellent mechanical properties, PLA is already widely used in various sectors, including agriculture, textiles, and packaging. Despite these environmentally friendly characteristics, PLA still contributes to the plastic waste crisis due to its current waste management strategy, which follows a linear economic model. A more sustainable solution for PLA is chemical recycling, which allows the production of monomers and/or value-added materials, helping to establish a circular economic model that supports the growing use of this plastic. [1] Currently, hydrolysis and alcoholysis are the two most effective methods for treating PLA waste. Hydrolysis converts PLA into lactic acid, effectively closing its life cycle (route a). Alcoholysis, an efficient upcycling strategy, transforms PLA waste into alkyl lactate, sustainable solvents (route b). Furthermore, the use of diols such as ethylene glycol and 1,4-butanediol can lead to the production of polyols (route c), which are valuable in the manufacture of polyurethanes. [2] In our research group, zinc complexes bearing phenoxy-imino-pyridine ligands were developed that exhibited high activity both in PLA synthesis and its chemical recycling. In this work, their potential has been further enhanced, particularly in terms of sustainability, by employing microwave irradiation, which reduces reaction time and the alcohol ratio, while maintaining high selectivity towards the target products. Furthermore, catalyst recyclability tests supported their potential for continuous use in these processes. [4]