The Division of Chemistry supports William Ellis of Cornell University as an American Competitiveness in Chemistry Fellow. Dr. Ellis will work on developing Zn-based catalysts for the copolymerization of epoxides and carbon dioxide. He will collaborate with scientists at SEEO, a Berkeley, California-based battery company. The ultimate goal of this research is to develop polycarbonate highly isotactic polycarbonate materials for use as lithium-ion transport membrane materials in Li ion batteries. For his plan for broadening participation, the PI will develop a hands-on science kits to engage rural students in science. In this activity, the PI will collaborate with educators at the Cornell Center for Materials Research.
Research like that of Dr. Ellis is aimed at developing new kinds of materials for lithium ion batteries, an increasingly important technology. The particular chemistry that Dr. Ellis is developing is "green" in that it uses an earth-abundant element (zinc) that has low toxicity as the transition metal in his catalysts, and one of his feedstock chemicals is carbon dioxide. The efforts at broadening participation being pursued by Dr. Ellis are aimed at giving underrepresented students in rural areas hands-on activities in important areas of science.
This award allowed the PI to engage in a long term postdoctoral research project under the guidance of a highly accomplished Professor of Chemistry, Geoff Coates at Cornell University. The freedom that came along with the financing underpinned the success of this project by providing ample acces to starting materials and instrumentation to push the high risk project forward at a rapid pace. Initial success was obtained in the first year of the grant with the discovery of a highly active catalyst family that yielded the target polymer of this proposal, ie isotactic poly(cyclohexene carbonate). The second year of this funding allowed the PI to optimize this catalyst family so as to acheive almost 2-orders of magnitude increase in rate, increased molecular weight of the resulting polymer, and also much higher isotacticity. In the last stages of the research, polymer properties were just beginning to be measured and a strong correlation between tacticity and melting temperature was observed, thus informing potential manufacturing processing. The outcome of this work is: 1 full manuscript that is nearing submission to a top tier journal (abstract is shown below), 2 mentored graduate students who will be coauthors, and an incredible postdoctoral experience that will shape the rest of the PI's scientific life. The PI was able to attend two conferences (Gordon Organometallics 2012 and Summer 2012 ACS). He presented a talk at both of them, which was well received and provided valuable feedback to shape the research. In the summer of 2013, the PI began his career as an Associate Scientist at Phillips 66 in Bartlesville, OK. ABSTRACT: We report a family of catalysts for the enantioselective copolymerization of CO2 and aliphatic meso epoxides. C1 symmetric zinc b-diiminate catalysts were discovered and optimized using structure-activity relationships and iterative ligand design. The optimized catalysts form highly isotactic poly(cyclohexene carbonate) under mild conditions. A diblock copolymer of CO2/cyclohexene oxide and CO2/cyclopentene oxide was synthesized, demonstrating the controlled behavior of the catalysts. Solid-state structures and solution state dynamics help explain trends in turnover frequencies. A strong correlation between isotacticity and melting temperature is observed. X?ray powder diffraction was used to measure crystallinity and study the changes in morphology observed upon annealing.
