Polymer, Vol.167, 193-201, 2019
Nanoporous-crystalline films of PPO with parallel and perpendicular polymer chain orientations
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(perpendicular to)) 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(perpendicular to) 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(perpendicular to) orientations, have allowed establishing the direction of transition moment vectors of polymer chain vibrational peaks. NC films with c(//) and c(perpendicular to) orientations, are expected to allow control of guest diffusivities as well as orientation of active guest molecules.
Keywords:Guest induced crystallization;Crystalline phase orientation;Poly(2,6-dimethyl-1,4-phenylene) oxide