Unleashing the power of non-toxic Zn-guanidine catalysts for sustainable lactide polymerization through smart modeling

Polylactide (PLA) is one of the most promising bioplastics and is therefore often quoted as a solution to fight today's global plastics crisis. However, current PLA production via the ring-opening polymerization (ROP) of lactide is not yet sustainable since it heavily relies on the toxic catalyst tin octoate. To overcome the hurdles in scale-up and to accelerate the transition of promising new non-toxic alternative ROP catalysts from laboratory to industry, model-based analysis is a highly effective tool. Herein, our previously introduced kinetic model for the ROP of L-lactide using a non-toxic and robust Zn guanidine "asme"-type catalyst under industrially relevant melt conditions is expanded upon using two new co-initiators. The experimental data is evaluated using "traditional" kinetic analysis following pseudo-first-order kinetics to approximate a relationship between co-initiator concentration and the rate of polymerization. The range of validity of these findings is considerably expanded by taking model data into account to compare the performance of the different co-initiators in lactide ROP.