Discipline: Chemistry and Chemical Sciences
Subcategory: Chemistry (not Biochemistry)
Marco S. Messina - University of California, Los Angeles (UCLA)
Co-Author(s): Paul Chong, Alex Wixtrom, Raymond Wang, Kent Kirlikovali, Jonathan C. Axtell, Anastassia N. Alexandrova, Heather D. Maynard, and Alexander M. Spokoyny, UCLA, Los Angeles, CA Charles W. Machan and Clifford P. Kubiak, UCSD, San Diego, CA
We have recently discovered that metal-free boron-rich clusters can be used as efficient photo-catalysts for olefin polymerization. These cluster species undergo photo-excitation with visible light allowing to initiate and propagate cationic polymerization of styrene monomers. The boron cluster photo-catalysts can be synthesized on a gram scale in two steps from commercially available precursors and are stable to air and moisture. A variety of polymers were synthesized by utilizing these catalysts at a concentration as low as 0.005 mol%. Unlike in the case of recently reported examples from Nicewicz and co-workers utilizing pyrilium photo-catalyst, this system is capable of polymerizing both electron-rich and –poor styrene substrates providing a convenient access to polymers in nearly quantitative yields (>90% ± 5%), relatively low dispersities (Ð =1.2-2.2) and molecular weights (Mn) between 8 and 30 kDa. Our system offers lower catalyst loading over previously developed systems, improved monomer scope, ease of photo-catalyst preparation, and ease of polymer purification as the photo-catalyst is readily soluble in most organic solvents. Current efforts are aimed at optimizing conditions for polymerization to target block-copolymer architectures and understanding precise mechanism governing this unprecedented reactivity.
MSM_ERN_Abstract.docxFunder Acknowledgement(s): NSF Bridge-to-Doctorate UCLA Graduate Division UCLA Chemistry and Biochemistry Department
Faculty Advisor: Alexander M. Spokoyny, spokoyny@chem.ucla.edu