A series of polyimide precursors, poly(amic acid)s, containing propyltrimethoxysliane at two chain ends were prepared from 4,4 '-bis(4-amino-2-trifluoromethylphenoxy)biphenyl (1) with six commercially available dianhydrides, followed by end-capping with 3-ammopropyltrimethoxysilane (APrTMOS). A new class of fluorine-containing polyimide /silica composite films (III) with chemical bonds between the fluorinated polyimide backbone and the silica network has been synthesized from the APrTMOS-terminated precursors with tetramethoxysilane via the sol-gel process and thermal cyclodehydration. The resultant hybrid films were light-colored, flexible, and tough. They had high levels of thermal stability associated with high glass-transition temperatures (> 251 degrees C), 10% weight-loss temperatures in excess of 527 degrees C, and char yields at 800 degrees C in nitrogen higher than 60%. For a comparative study, the analogous nonfluorinated polyimide/silica hybrid films (III '), based on 4,4 '-bis (4-aminophenoxy)biphenyl (I ') and the neat fluorinated polyimide films (IV), based on diamine I, were also synthesized and characterized. The hybrid films of the fluorinated series III showed a higher transparency and less color intensity when compared with the nonfluorinated III ' analogs. They also revealed a lower refraction index and birefringence than pure polyimides (IV). (C) 2007 Wiley Periodicals, Inc.