Uniplanar Orientations and Guest Exchange in PPO Cocrystalline Films

Abstract

Guest-induced cocrystallization of amorphous poly(2,6-dimethyl-1,4-phenylene ether) (PPO) films has been investigated, mainly by X-ray diffraction and FTIR spectroscopy. Two different kinds of uniplanar orientations have been found for PPO cocrystalline phases with α-pinene, which present their (110) and (200) crystal planes preferentially parallel to the film plane (f110 = 0.90 and f200 = 0.75, respectively). Both kinds of uniplanar orientations can be fully retained after guest-exchange procedures leading to cocrystalline forms, which maintain unaltered the polymer host conformation, like those with decalin or tetralin. The formation of different kinds and high degrees of uniplanar orientations, as until now observed only for syndiotactic polystyrene cocrystallization, suggests that solvent-induced uniplanar orientations, for high film thickness and without any mechanical process, are generally associated with the formation of polymer cocrystalline phases.