Synthesis of air-stable poly(benzonorbornadiene)s via ring-opening metathesis polymerization

Herein, air-stable poly(benzonorbornadiene) was synthesized via ring-opening metathesis polymerization. Conventional poly(benzonorbornadiene) easily decomposed in the presence of molecular oxygen owing to the generation of radicals at allylic and benzylic hydrogens. However, our sterically bulky aryl-group substituents of polymers physically blocked the access of oxygen at these positions. The resulting polymers preserved their backbones for more than 2 weeks in air. Postmodification of bromophenyl-substituted polymer successfully afforded the expanded aryl substituted polymer by Suzuki-Miyaura coupling with phenylboronic acid in the presence of Pd catalyst. With this highly air-stable polymers, development of fully conjugated all-carbon polymer is currently being studied.