Extremely High Molar Mass Hyperbranched Poly(arylene ether)s from a New Semifluorinated AB2 Monomer by an Unusual AB2 + A2 Polymerization Approach

A new AB(2) monomer [3,5-bis(4-fluoro-3-trifluoromethylphenyl)phenol] has been successfully prepared by the Pd(0)-initiated coupling reaction of 4-fluoro-3-trifluoromethylphenylboronic acid and 3,5-dibromophenol. This monomer led to a high molecular weight hyperbranched polymer (M-w = 230 000 g/mol) by self-condensation. Several hyperbranched polymers have also been prepared successfully by condensing the AB(2) monomer with different diphenols (A(2)) in different molar ratios. Here, the stoichiometric (2:1) AB(2)/A(2) products 2c and 3c showed extremely high weight-average molecular weights of 3 730 000 and 4470000 g/mol without any gelation under the specified reaction conditions. The products have been well characterized by SEC, DSC, TGA, FTIR, and NMR techniques. The degree of branching of the AB(2) product could be determined by proton NMR for a medium molar mass sample and was found to be 0.5. The AB, self-condensed hyperbranched poly(arylene ether) showed a glass transition temperature (T-g) as high as 199 degrees C and the 10% weight loss temperature as high as 573 degrees C in N-2, whereas the extremely high molar mass products 2c and 3c of the AB(2)/A(2) approach did not show a T-g up to 350 degrees C and similar high thermal stability. Homogenous and stable films could be prepared from these new polymers which are prone to self-cross-linking by heating especially for the AB(2)/A(2) products. High hydrophobicity of the polymers combined with high thermal stability renders those materials highly interesting for microelectronics application.