SusChEM: Stereoselective Polymerization of Biomass Monomers by Transition-Metal and Organic Catalysts

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The Chemical Catalysis Program supports the efforts of Professor Eugene Y. Chen of Colorado State University in the investigation of new stereoselective polymerization systems by chiral transition-metal and organic catalysts for the synthesis of high-value stereoregular and chiral polymers or optically-resolved chemicals from biomass-derived acrylic monomers in a catalytic fashion. Synthetic, catalytic, mechanistic, and computational methods are employed to accomplish three specific objectives: (1) establishing stereoselective polymerization of biomass acrylics through molecular engineering of chiral transition-metal catalysts; (2) advancing hydride-shuttling polymerizations promoted by chiral ion pairs to enable catalytic polymerization of biomass acrylics and catalytic asymmetric polymerization of bulky acrylics; and (3) developing catalytic and asymmetric organopolymerizations of acrylics via internal and external chain transfer routes and utilization of chiral organic catalysts. Diverse experimental techniques are coupled with international collaborations that bring in complementary theoretical expertise. This project falls under the SusChEM initiative as it utilizes non-petroleum based starting materials (e.g., plant biomass) for the production of potential commodity-scale products. This research provides educational opportunities for training and teaching of students with a wide range of techniques in catalysis and polymeric materials, areas central to the global economy. Students also learn about sustainability, providing them with a strong basis to address global problems and play leadership roles in their future professional workplaces.The Chemical Catalysis Program supports the efforts of Eugene Y. Chen of Colorado State University for the investigation of metal-and organically-catalyzed polymerization of acrylics. The metal-catalyzed route departs from conventional (anionic or radical) acrylic polymerizations in three ways: (a) it is catalyst site-controlled so that molecular catalysts can be engineered for the synthesis of a wide range of polymers with high precision at room temperature; (b) it ensures the same degree of chiral induction for each monomer to produce uniform chiral polymers; and (c) catalytic cycles can be constructed by internal or external processes for catalytic production of stereoregular or chiral polymers. The organocatalysis route exhibits characteristics that embody several key principles of sustainable/green chemistry: it employs only a small amount of the relatively non-toxic organic catalyst and rapidly converts all monomers to high molecular weight bioplastics in less than 1 min of reaction at room temperature. From a technological point of view, both polymerization systems can be operated under economically viable conditions (e.g., at lower temperatures and in a catalytic fashion) and produce technologically important stereoregular or chiral polymers using renewable feedstocks, which offer not only sustainable alternatives to petroleum-based polymers, but also superior materials properties. Professor Chen is preparing a new textbook for senior undergraduate and graduate level students on the "Chemistry of Sustainability". This text is envisioned for use in educating chemistry and chemical engineering students as well as the general public in the central role of chemistry in sustainability.