Efficient synthesis of rigid ladder polymers via palladium catalyzed annulation.

We report a new method to synthesize rigid ladder polymers using efficient palladium catalyzed annulation reactions with low catalyst loading (1 mol %). Rigid ladder polymers with benzocyclobutene backbone linkages can be synthesized from copolymerization of readily accessible aryl dibromides and norbornadiene or polymerization of AB type monomers bearing norbornene and aryl bromide or triflate moieties. High molecular weight (10-40 kDa) rigid ladder polymers can be obtained with complete monomer conversions. Diverse monomers also gave different, fixed ladder polymer conformations. The ladder polymers exhibited excellent thermal stability, high carbonization yield, and large intrinsic porosity.