Chemistry Colloquium with Lilliana Morris ’14, Cornell University

“Bimetallic Catalysts and Chain Shuttling Agents: Controlled Access to Isotactic Poly (propylene oxide)”

Poly (propylene oxide) (PPO) accounts for 5% of polymer production worldwide with 14 million tons produced in 2011. Although commercially successful for the synthesis of polyurethane foams, the vast majority of PPO manufactured is low molecular weight and atactic. A wide range of polymer properties could potentially be accessed through control of molecular weight and tacticity. Although production of isotactic PPO was reported in 1949, the heterogeneous catalysts only produced some partially isotactic material with atactic byproduct. In 2005, the Coates group reported the first production of highly isotactic PPO. While this bimetallic catalyst showed excellent selectivities with a wide range of epoxides, there was little control over the molecular weight and dispersity of the polymers. Through the use of new catalyst systems, we have developed a method for the production of isotactic PPO with excellent control over molecular weight and dispersity.