Poly[thio-1,4-(phenylenethio)perfluoroalkane], poly[thio-1,4-phenyleneoxy-1,4-(phenylenethio) perfluoroalkane], and poly(phenylene sulfide)-block-[poly(tetrafluoroethylene-c vinyl ether)])-block-poly(phenylene sulfide) are synthesized by oxidative cationic polymerization. Poly[thio-1,4-phenyleneoxy-1,4-(phenylenethio)perfluorohexane] (T-g, 34 degrees C; T-m, 144 C; T-d10%, 394 degrees C; M(w), 57 000) is completely oxidized to poly[sulfonyl-1,4-phenyleneoxy-1,4-(phenylenesulfonyl)perfluorohexane] (T-g, 147 degrees C; T-d10%, 395 degrees C; M(w), 48 500) using H2O2/CF3COOH (1/1 = v/v). Poly(TFE-co-PVE) copolymer (M(w), 6000) linking poly[methyl 4-[(phenylthio)phenyl]sulfonium trifluoromethanesulfonate](polysulfonium cation) at both sides is synthesized through the copolymerization with methyl C(phenylthio)phenyl sulfoxide. The block prepolymer is converted to poly(phenylene sulfide)-block-[poly(tetrafluoroethylene-c (propyl vinyl ether)]-block-poly(phenylene sulfide) (T-g, 90 degrees C; T-c, 138 degrees C; T-m, 276 degrees C; T-d10%, 395 degrees C) by demethylation of the polycation.