Synthesis and characterization of poly[[l,1′-biphenyl]-4,4′-diyl[2,2,2-trifluoro-l-(trifluoromethyl) ethylidene]]
ABSTRACT: A new high-performance material, poly[[1,1′-biphenyl]-4,4′-diyl[2,2,2-trinuoro-l-(trinuoromethyl) ethylidene]] (PDTFE), was prepared by Ni(0)-catalyze_d coupling of 2,2-bis(p-chlorophenyl)hexafluoropropane. The resulting high molecular weight polymer (Mn of 19.2 × 103 g/mol by gel permeation chromatography and 27.5 × 103 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 cm3 (STP)cm/(cm2·s-cmHg) and an O2/N2 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. © 1999 American Chemical Society.
Havelka-Rivard, PA; Nagai, K; Freeman, BD; Sheares, VV
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