Highly Soluble Fluorinated Polyimides Based on an Asymmetric Bis(ether amine): 1,7-Bis(4-amino-2-trifluoromethylphenoxy)naphthalene

A novel structurally asymmetric bis(ether amine) monomer containing trifluoromethyl groups, 1,7-bis(4-amino-2-trifluoromethylphenoxy)naphthalene, was prepared through the nucleophilic substitution reaction of 2-chloro-5-nitrobenzotrifluoride and 1,7-dihydroxynaphthalene in the presence of potassium carbonate in N-methyl-2-pyrrolidone (NMP), followed by catalytic reduction with hydrazine and Pd/C in ethanol. A series of new fluorine-containing polyimides were synthesized from the diamine with various commercially available aromatic tetracarboxylic dianhydrides using a two-stage process with thermal or chemical imidization method. The intermediate poly(amic acid)s had inherent viscosities between 0.93 and 1.93 dL/g. Most of the polyimides obtained from both routes were readily soluble in many organic solvents such as NMP and N,N-dimethylacetamide (DMAc). All the polyimides could afford transparent, flexible, and strong films with low moisture absorptions of 0.29-0.69%, low dielectric constants of 2.81-3.23 at 10 kHz, and an ultraviolet-visible absorption cutoff wavelength at 358-423 nm. The glass-transition temperatures (T(g)s) (by DSC) and softening temperatures (by thermomechanical analysis) of the polyimides were recorded in the range of 222-271 degrees C and 210-266 degrees C, respectively. Decomposition temperatures for 10% weight loss all occurred above 500 degrees C in both nitrogen and air atmospheres. For a comparative study, some properties of the present polyimides will be compared with those of structurally related ones derived from 1,7-bis(4-aminophenoxy)naphthalene and 1,5-bis(4-amino-2-trifluoromethylphenoxy)naphthalene. 02009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 1756-1770, 2009