Poly(p-phenylene) via ‘Living’ Polymerization

Significance

Yokozawa and co-workers prepare a poly(p-phenylene) with narrow polydispersity and controlled molecular weight via nickel-catalyzed polymerization. The authors have previously reported a similar system for regioregular poly(3-hexyl)thiophene synthesis (T. Yokozawa and co-workers Macromolecules 2004, 37, 1169-1171). The procedure relies on the near quantitative Grignard metathesis reaction between i-PrMgCl and a dibromoarene to generate the monomer. Adding an equivalent of LiCl accelerated the polymerization and decreased the polydispersity. The authors propose that LiCl disrupts the monomer homo­aggregates. The molecular weight increased with subsequent monomer addition, confirming the chain-growth mechanism.