Synthesis and characterization of poly[[1,1 prime -biphenyl]-4,4 prime -diyl[2,2,2-trifluoro-1- (trifluoromethyl)ethylidene]]

摘要

A new high-performance material, poly[[1,1 prime -biphenyl]-4,4 prime ,diyl[2,2,2-trifluoro-1- (trifluoromethyl)ethylidene]] (PDTFE), was prepared by Ni(0)-catalyzed coupling of 2,2-bis(p-chlorophenyl)-hexafluoropropane. The resulting high molecular weight polymer (M_n of 19.2×10~3 g/mol by gel permeation chromatography and 27.5×10~3 g/mol by multiple-angle laser light scattering) is amorphous and soluble in a number of common organic solvents including tetrahydrofuran, chloroform, and acetone. The solubility leads to ease of preparation, characterization, and processing of PDTFE. Excellent thermal properties were exhibited with a glass transition temperature of 255 °C and 10% weight loss values of 533 and 535 °C in nitrogen and air, respectively. The flame-retardant properties showed that the material meets the Federal Aviation Administration's current criteria for heat release capacity, total heat release, and char yield for flame-retardant materials. Additionally, colorless, transparent, creasable films were cast from chloroform. The film formation of PDTFE made the gas permeability measurements possible. PDTFE has a rather high oxygen permeability coefficient of 120×10~(-10) cm~3 (STP)cm/(cm~2·s·cmHg) and an O_2/N_2 selectivity of 2.9 at 35 °C. The new material has an impressively low dielectric constant of 2.56. Finally, the new polymer is highly hydrophobic with no detectable water uptake after 24 h in boiling water. The combination of facile synthesis and an excellent property profile makes this a unique phenylene-based high-performance polymer that will lead to a series of novel fluorinated materials.