Catalysts as Key Enablers for the Synthesis of Bioplastics with Sophisticated Architectures

Bioplastics are one of the answers to environmental pollution and linear material flows. The most promising bioplastic polylactide (PLA) is already replacing conventional plastics in a number of applications. The properties of PLA, however, do not fit for all potential application areas, but they can be altered by the introduction of comonomers. The copolymerization of lactide (LA) with other lactones like epsilon-caprolactone (CL) has been established for several years. Nevertheless, controlling copolymerizations remains a challenge due to the high complexity of the system. Copolymerization of LA with other monomer classes is much less investigated, but has the chance to overcome the limitations in material properties that occur when only lactones are used. The crucial factor for all copolymerizations is the catalyst. It dominates the reaction kinetics and determines the resulting microstructure. In this review, copolymerization catalysts for LA are presented divided into catalysts for the synthesis of lactone block copolymers, lactone random copolymers, and multimechanistically synthesized copolymers. The selected catalysts are highlighted either owing to their industrially applicable polymerization conditions or their non-standard mechanism.

Automated summary

Bioplastics, such as polylactide (PLA), offer a solution to environmental pollution and linear material flows as they can replace conventional plastics in various applications. The properties of PLA can be altered by introducing comonomers, including other lactones like epsilon-caprolactone (CL). However, controlling copolymerizations of lactide (LA) with other monomer classes remains challenging due to the complexity of the system. Catalysts play a crucial role in copolymerizations, determining the reaction kinetics and resulting microstructure. This review presents copolymerization catalysts for LA, categorized into catalysts for lactone block copolymers, lactone random copolymers, and multimechanistically synthesized copolymers.