Chain‐growth polycondensation of potassium 3‐cyano‐4‐fluorophenolate derivatives for well‐defined poly(arylene ether)s

Polycondensation normally proceeds in a step-growth reaction manner to give polymers with a wide range of molecular weights. However, the polycondensation of potassium 2-alkyl-5-cyano-4-fluorophenolate (1) proceeded at 150 °C in a chain polymerization manner from initiator, 4-fluoro-4'-trifluoromethyl benzophenone (2), to give aromatic polyethers having controlled molecular weights and low polydispersities (M w /M n < 1.2). The resulting polycondensation of 1 had all of the characteristics of living polymerization and displayed a linear correlation between molecular weight and monomer conversion, maintaining low polydispersities. Sulfolane was a better solvent for chain-growth polycondensation of 1 than other aprotic solvents. The polyether from 1 with a low polydispersity showed higher crystallinity than that with a broad molecular weight distribution, obtained by the conventional polycondensation of 1 without 2.