Sustainable Polymerization Catalysis for Advanced Biorenewable Polymeric Materials

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Project Overview: Polymerization catalysis is the most efficient, economical synthesis technique to convert building block chemicals into polymers, materials essential to virtually all aspects of modern life and the global economy. Most current polymerization processes employed for the synthesis of synthetic polymers utilize predominantly depleting petroleum-based feedstocks as well as rare, expensive, or toxic metal catalysts and/or enviromentally polluting processes, therefore, are unsustainable. The Central Objective of this IUPAC (US-China-Germany) Team project is to develop sustainable polymerization catalysis, through designing earth-abundant, environmentally benign metal and non-toxic organic catalysts as well as highly efficient polymerization systems, to access advanced, novel biorenewable and biodegradable polylactide (PLA) materials.Intellectual Merit: The intellectual merit of the proposed research is threefold. First, the proposed bifunctional chiral organocatalysts, based on naturally occurring or synthetically modified cinchona alkaloids, for kinetic resolution polymerization or enantioselective polymerization of racemic lactide will simultaneously produce chiral poly(L-LA) and optically resolved unnatural (expensive) D-LA, or highly crystalline poly(L-LA)/poly(D-LA) stereocomplex. Second, the development highly efficient immortal polymerization systems enabled by bio-benign metal catalysts and designer chain transfer agents will achieve novel functional and topological PLA materials in a highly efficient, catalytic fashion. Third, molecularly engineered earth-abundant metal complexes with specific functions will promote stereoselective polymerization of lactide leading to highly stereoregular, high-performance PLAs.Broader Impacts:The broader impacts of this research include: (a) discovery and understanding in chemical catalysis and synthesis, polymer chemistry and polymerization mechanism, as well as biomaterials and sustainability; (b) society and environment, as this work is in sustainable catalysis for renewable polymers, materials essential to modern life and the global economy; (c) international collaboration that enables scientists with complementary expertise and facilities required to solve complex problems together; and (d) education of graduate students and postdoctoral researchers with the needed skills to thrive in the global sustainability workplace.