Polymeric Films with Three Different Orientations of Crystalline-Phase Empty Channels

The uniplanar orientations that can be achieved for the ε phase of syndiotactic polystyrene, i.e., the first polymeric crystalline phase exhibiting channel-shaped porosity, have been explored by wide-angle X-ray diffraction. The formation of three different uniplanar orientations, presenting the three unit-cell axes perpendicular to the film plane, can be controlled by suitable processes, which are based on combined solvent-induced crystallizations and on thermal treatments. This allows gaining control of three different orientations of the crystalline nanochannels with respect to the film surface and hence control of diffusivity as well as orientation of low-molecular-mass guest molecules, also at the macroscopic scale.