Journal of Polymer Science Part A: Polymer Chemistry, Vol.42, No.10, 2377-2394, 2004
Preparation and properties of new polyimides and polyamides based on 1,4-bis(4-amino-2-trifluoromethylphenoxy) naphthalene
A novel, trifluoromethyl-substituted, bis(either amine) monomer, 1,4-bis(4-amino-2-trifluoromethylphenoxy)naphthalene, was synthesized through the nucleophilic displacement of 2-chloro-5-nitrobenzotrifluoride with 1,4-dihydroxynaphthalene in the presence of potassium carbonate in dimethyl sulfoxide, followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new fluorine-containing polyimides with inherent viscosities of 0.57-0.91 dL/g were prepared by reacting the diamine with six commercially available aromatic dianhydrides via a conventional, two-step thermal or chemical imidization method. Most of the resulting polyimides were soluble in strong polar solvents such as N-methylpyrrolidone and N,N-dimethylacetamide (DMAc). All the polyimides afforded transparent, flexible, and strong films with good tensile properties. These polyimides exhibited glass-transition temperatures (T-g's) (by DSC) and softening temperatures (by thermomechanical analysis) in the ranges of 252-315 and 254-301 degreesC, respectively. Decomposition temperatures for 5% weight loss all occurred above 500 degreesC in both air and nitrogen atmospheres. The dielectric constants of these polyimides ranged from 3.03 to 3.71 at 1 MHz. In addition, a series of new, fluorinated polyamides with inherent viscosities of 0.32-0.62 dL/g were prepared by the direct polycondensation reaction the diamine with various aromatic dicarboxylic acids by means of triphenyl phosphite and pyridine. All the polyamides were soluble in polar solvents such as DMAc and could be solution-cast into tough and flexible films. These polyamides had T-g's between 228 and 256 degreesC and 10% weight-loss temperatures above 400 degreesC in nitrogen or air. (C) 2004 Wiley Periodicals, Inc.
Keywords:trifluoromethyl;fluoropolymers;1,4-dihydroxynaphthalene;polyimides;polyamides;high-temperature polymeric materials;dielectric constants;solubility;thermal properties;structure-property relations