Solvent-Assisted Poly(lactic acid) Upcycling under Mild Conditions

Poly-(lactic acid) (PLA) is a biosourced green plasticderived fromnatural sources that can replace polyolefins in many applications;however, it is seldom recycled. PLA is a prime candidate for chemicalrecycling by depolymerization, which produces valuable commodity chemicalsand/or fresh monomer for new production, compared to mechanical/thermalreprocessing which produces lesser-quality resin. A scalable, low-costdepolymerization process could render PLA the premier choice for designed-to-be-recycledproducts in a future circular plastics economy. Here, we report anovel process for depolymerization of PLA under mild conditions usingalcoholysis with ionic liquid catalysts in the presence of dimethyl(or diethyl) carbonate as a green solvent, along with critical technoeconomicanalysis of the potential impact of this process. The effects of catalyststructures, the solvent system, and PLA resin type on conversion andyield were studied. The reaction kinetics were statistically analyzedwith experimental and modeling data, suggesting a fast first-orderreaction in PLA degradation. Predictive modeling results based onempirical data further guide the design of scenarios and potentialfor practical application. Ionicliquids can be used to recycle poly-(lactic acid) (PLA)under mild conditions and reduced greenhouse gas emissions.

Automated summary

Poly(lactic acid) (PLA) is a biodegradable plastic derived from natural sources that can replace polyolefins in various applications. A novel process using ionic liquid catalysts and dimethyl (or diethyl) carbonate as a green solvent was developed for depolymerization of PLA under mild conditions, which enables efficient recycling of PLA and helps reduce greenhouse gas emissions.