Synthesis and properties of novel soluble fluorinated aromatic polyamides containing 4-benzoyl-2,3,5,6-tetrafluorophenoxy pendant groups

摘要

A new diaroyl chloride monomer, 5-(4-benzoyl-2,3,5,6-tetrafluorophenoxy) isophthaloyl dichloride (BTFPIPC), was prepared in a three-step synthesis. Six novel aromatic polyamides containing 4-benzoyl-2,3,5,6-tetrafluorophenoxy pendant groups were synthesized by low temperature polycondensation of BTFPIPC with six aromatic diamines in N, N-dimethylacetamide (DMAc). All these new polymers are amorphous and readily soluble in various dipolar solvents such as DMAc, N-methyl-2-pyrrolidinone (NMP), N, N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) at room temperature. These polymers showed glass transition temperatures between 212 and 243 degrees C and 5% weight loss temperatures ranging from 439 degrees C to 456 degrees C. These polyamides could be cast into transparent, flexible and strong films from DMAc solution with tensile strengths of 73.5-85.4 MPa, tensile moduli of 2.06-2.72 GPa, and elongations at break of 6.4-9.3%. These new polyamide films exhibited low dielectric constants of 3.26-3.57 (1 MHz), lower water uptakes in the range of 1.27-2.28%, and excellent transparency with an ultraviolet-visible absorption cut-off wavelength in the 326-373 nm range. Primary characterization of these new polyamides shows that they might serve as new candidates for processable high-performance polymeric materials.