Nanoporous-crystalline films of PPO with parallel and perpendicular polymer chain orientations

Abstract

Oriented nanoporous crystalline (NC) phases of poly(2,6-dimethyl-1,4-phenylene) oxide (PPO) are for the first time described. In particular, PPO films with orientations of crystalline chain axes preferentially parallel (c//) or perpendicular (c⊥) to the film plane are obtained by suitable procedures of solution casting or of solvent-induced crystallization, respectively. 2D-WAXD patterns of NC PPO films, exhibiting c// and c⊥ orientations, have allowed indexing of reflections and establishing unit cell parameters of NC modifications (e.g., for the NC modification from carvone an orthorhombic unit cell with a = 1.97 nm; b = 1.24 nm; c = 0.53 nm). FTIR spectra of NC PPO films exhibiting c// or c⊥ orientations, have allowed establishing the direction of transition moment vectors of polymer chain vibrational peaks. NC films with c// and c⊥ orientations, are expected to allow control of guest diffusivities as well as orientation of active guest molecules.