Poly(phenylene oxide) Films with Hydrophilic Sulfonated Amorphous Phase and Physically Cross-Linking Hydrophobic Crystalline Phase

Poly(phenylene oxide) (PPO) films with hydrophilic sulfonated amorphous phase and physically cross-linking hydrophobic crystalline phase are obtained by solid-state film sulfonation. Semicrystalline-sulfonated PPO (SPPO) films show hydrothermal and solvent stability much higher than for amorphous SPPO films. These semicrystalline SPPO films exhibit a nanoporous-crystalline (NC) α form and much faster guest sorption kinetics with respect to unsulfonated NC films. Unoriented NC SPPO films can be prepared by solid-state sulfonation of fully amorphous PPO films, by simultaneous PPO sulfonation and guest-induced cocrystallization. NC SPPO films with crystalline polymer helices preferentially perpendicular to the film plane (c⊥ oriented), can be obtained by solid-state sulfonation of c⊥ NC PPO films. c⊥-oriented NC SPPO films, with respect to unoriented NC SPPO films, have the advantages of faster sulfonation kinetics, higher film transparency, and faster organic guest uptakes.