Macromolecular Synthesis

Metal-free Atom Transfer Radical Polymerization

In order to overcome the challenge of metal contamination in traditional ATRP systems, we have been involved in developing a metal-free ATRP process, mediated by light and catalyzed by an organic-based photoredox catalyst. Polymerization of vinyl monomers are efficiently activated and deactivated with light leading to excellent control over the molecular weight, polydispersity, and chain ends of the resulting polymers. Significantly, block copolymer formation is facile and can be combined with other controlled radical processes leading to structural and synthetic versatility. We believe that these new organic-based photoredox catalysts will enable new applications for controlled radical polymerizations and are exploring their further value in both small molecule and polymer chemistry. 

New Building Blocks for Polymer Electronics Materials

New conjugated molecules with twisted structures have been designed and synthesized. Copolymers with these nonplanar building blocks are unique in terms of their optical and electrochemical properties. These new polymer materials have found their applications in organic electronics such as solar cells, field-effect transistors and thermoelectrics.

Chain-end Modification of Polymers

We report a metal-free strategy for the chain-end modification of polymers utilizing visible light. The versatility of this process is exemplified by application to a wide range of polymer backbones under mild, quantitative conditions using commercial reagents.

Functional Polyethers

Polyethers, such as poly(ethylene glycol) (PEG), are widely used materials in established fields such as drug-delivery, and control of biocompatibility, and are becoming increasingly important in emerging technologies such as lithium-polymer batteries, and environmentally benign anti-biofouling coatings. A challenge with all PEG-based systems is the lack of functional handles along the polyether backbone. Using robust monomer syntheses, and highly controlled ring-opening (co) polymerizations, we are able to tailor the functionality of polyether materials toward applications in drug-delivery, and energy storage.

Functional Polyethers