Novel Aromatic Polymers with Pentafluorophenyl Pendent Groups

A novel series of linear, high-molecular-weight polymers was synthesized by one-pot, superacid-catalyzed reaction of pentafluorobenzaldehyde (PFBA) (1) with nonactivated aromatic hydrocarbons: biphenyl, dipheryl ether, p-terphenyl, 4,4'-diphenoxybenzophenone, and 1,3-bis- and 1,4-bis(4'-phenoxybenzoyl)benzenes. The reactions were performed at room temperature in the Bronsted superacid trifluoromethanesulfonic acid (CF3SO3H, TFSA) and in a mixture of TFSA with methylene chloride. The polymer-forming reaction was highly dependent upon the acidity of the reaction medium, as judged from the molecular weights of the polymers obtained. A possible reaction mechanism is suggested. The polymers obtained were soluble in the common organic solvents, and flexible transparent films could be cast from the solutions. H-1 and C-13 NMR analyses of the polymers synthesized revealed their linear structure. The pendent pentafluorophenyl groups react regioselectively with nucleophiles under basic conditions in polar, aprotic solvents. Side-chain-type sulfonated polymers were obtained from reaction with sodium 4-hydroxybenzenesulfonate.