Poly(4'-fluoro-2,5-benzophenone) was synthesized by Ni(0) catalytic coupling and was reacted with various nucleophiles by aromatic substitution (SNAr) to produce substituted poly(p-phenylene) thermoplastics. Substitution by the nucleophiles was determined in most cases to be nearly quantitative by gel permeation chromatography, H-1 NMR, and F-19 NMR. The number-average molar masses of the derivatized polymers by gel permeation chromatography and multiangle laser light scattering ranged from 27.1 x 10(4) to 31.4 x 10(4) g/mol. The largest increase in the glass transition temperature, relative to that of poly(4'-fluoro-2,5-benzophenone) was from 167 to 225 degrees C after displacement of fluoride by piperidine to give poly(4'-piperidino-2,5-benzophenone). The storage modulus of poly(4'-fluoro-2,5-benzophenone) was determined to be approximately 7.4 GPa at 50 degrees C by dynamic mechanical analysis, while the storage modulus of the improved film-forming 4-tert-butylphenoxy derivative (T-g = 170 degrees C) was 6.4 GPa at 50 degrees C.