Processable and colorless fluorinated poly(ether imide)s based on an isopropylidene-containing bis(ether anhydride) and various aromatic bis(ether amine)s bearing trifluoromethyl groups

A series of novel organosoluble and light-colored fluorinated poly(ether imide)s (PEIs) (IV) having inherent viscosities of 0.43-0.59 dL/g were prepared from 4,4'-[1,4-phenylenbis(isopropylidene-1,4-phenyleneoxy)]diphthalic anhydride (1) and various trifluoromethyl-substituted aromatic bis(ether amine)s by a standard two-step process with thermal and chemical imidization of poly (amic acid) precursors. These PEIs showed excellent solubility in many organic solvents and could be solution-cast into transparent and tough films. These films were essentially colorless, with an UV-visible absorption edge of 361375 nm and a very low b* value (a yellowness index) of 15.3-17.0. They also showed good thermal stability with glass-transition temperature of 191-248 degrees C, 10% weight loss temperature in excess of 494 degrees C, and char yields at 800 degrees C in nitrogen more than 39%. The thermally cured PEI films showed good mechanical properties with tensile strengths of 83-96 MPa, elongations at break of 8-11%, and initial moduli of 1.7-2.0 GPa. They possessed lower dielectric constants of 3.25-3.72 (1 MHz). In comparison with the V series nonfluorinated PEIs, the IV series showed better solubility, lower color intensity, and lower dielectric constants. (c) 2007 Wiley Periodicals, Inc.