Novel poly(paraphenylene)s via nucleophilic aromatic substitution of poly(4′-fluoro-2,5-diphenyl sulfone)

Poly(4'-fluoro-2,5-diphenyl sulfone) was synthesized via Ni(O)-catalyzed coupling and was reacted with various nucleophiles via aromatic substitution (SNAr) to produce derivatized poly(paraphenylene) (PPP) thermoplastics and thermosets. Substitution by the nucleophiles was determined to be nearly quantitative by GPC and H-1 NMR. The largest increase in the glass transition temperature relative to poly(4'-fluoro-2,5-diphenyl sulfone) was from 144 degreesC to 189 degreesC after displacement of fluoride with morpholine to give poly(4'-morpholino-2,5-diphenyl sulfone). Two graft copolymers were synthesized with low molecular weight poly(ethylene oxide) (PEO) and a poly(arylene ether ketone) (PAEK). The resulting PEO graft copolymer was soluble in water and in-polar, aprotic solvents. The PAEK graft copolymer produced transparent, creasable PPP-based films that had 5% weight loss temperatures in nitrogen and air of 510 and 513 degreesC, respectively. Furthermore, a PPP epoxy cure agent was synthesized by the reaction of 4-aminophenol with poly(4'-fluoro-2,5-diphenyl. sulfone). Finally, diethylenetriamine was reacted with poly(4'-fluoro-2,5-diphenyl sulfone) to produce a solvent resistant, cross-linked PPP film with a T-g of 240 degreesC.