Ae. Feiring et al., SYNTHESIS AND PROPERTIES OF FLUORINATED POLYIMIDES FROM NOVEL 2,2'-BIS(FLUOROALKOXY)BENZIDINES, Macromolecules, 26(11), 1993, pp. 2779-2784
New polyimides have been prepared from 2,2'-bis(fluoroalkoxy)benzidine
s and several dianhydrides. The new diamines, with fluoroalkoxy groups
OCF3, OCF2CF2H, and OCF2CFHOC3F7, were obtained from the correspondin
g 3-(fluoroalkoxy)nitrobenzenes by reduction to hydrazo derivatives, f
ollowed by benzidine rearrangements. High-quality polyimide films from
these diamines have been prepared by standard procedures and their th
ermal, mechanical, and electrical properties compared to known polyimi
des, including those derived from 2,2'-bis(trifluoromethyl)benzidine.
Polymers from the diamine with OCF3 substituents show an especially fa
vorable combination of low dielectric constant, moisture absorption, a
nd coefficient of thermal expansion (CTE) and high thermal stability,
suggesting promise as a next-generation material for electronics appli
cations. Polymers from diamines with the largest fluoroalkoxy substitu
tents have very low moisture absorption, but surprisingly high CTE.