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

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The Chemical Catalysis Program and the Macromolecular, Supramolecular, and Nanochemistry Program of the Chemistry Division support the project by Professor Eugene Chen. Professor Chen is a faculty member in the Department of Chemistry at Colorado State University. He is developing new methods of chemical catalysis for the synthesis of new types of plastics (polymers). These new plastics are renewable, meaning that they are prepared from grown feedstocks, and thus are sustainable. The second feature of these new polymers is that they have regular and well-controlled (stereoregular) chemical structures. Plastics with these characteristics have better physical properties for many applications. These two properties, stereoregularity and renewability, are important for new applications of plastics in the modern economy. The proposed research encompasses diverse areas of chemistry, materials science, and sustainability, thereby providing an excellent opportunity for training and teaching of students, including underrepresented minorities and undergraduate students.The proposed study addresses three currently unmet challenges still facing both the metal catalyzed and organocatalyzed polymerizations of acrylic monomers. First, existing chiral metal catalysts show high stereoselectivity in the polymerization of linear, petroleum-based acrylics but lack of stereochemical control over the polymerization of biomass-derived compact cyclic acrylics. Hence, the first specific objective of the work is to design advanced chiral transition-metal catalysts, assisted by theory, to enable stereoselective polymerization of such challenging bio-derived cyclic acrylic monomers. Second, the recently developed organocatalyzed proton-transfer polymerization can convert diacrylics uniquely into biodegradable unsaturated polyesters, but the current polyester product is an amorphous non-crystalline material, thus limiting its application. Accordingly, the second specific objective of the work is to develop the stereoselective proton-transfer polymerization for the synthesis of stereoregular crystalline unsaturated polyesters. Third, the current organocatalytic conjugate-addition polymerization of acrylic monomers produces only achiral acrylic polymers. Thus, the third specific objective of the work is to establish asymmetric organopolymerization of acrylic monomers to produce optically active chiral polymers. The education plan includes training and teaching of a diverse study body with complementary experimental and computational methods employed in this catalytic chemistry research, as well as for educating students and the general public about the central role of chemistry in addressing the global sustainability challenges.