Gas permeability of poly(4-methylpentene-1) in a confined nanolayered film system

In this study, multilayer films of sPS–PPS (syndiotactic Polystyrene and Polyphenylene sulfide blend) against P4MP1 [Poly(4-Methylpentene-1)] with various compositions and layer thicknesses were prepared by a layer multiplying coextrusion process. Incorporating the PPS into sPS layers before coextrusion produced pores in the sPS layers upon a post-extrusion, uniaxial orientation. Confined crystallization of P4MP1 by sPS–PPS was examined before and after the uniaxial orientation. A melt and recrystallization method was employed to achieve the preferred in-plane orientation of P4MP1 crystals. This was characterized by the atomic force microscopy and X-ray spectroscopy. We found that with P4MP1 layer thickness smaller than 400 nm, a confinement effect will induce in-plane P4MP1 crystal orientation where the crystal c-axis is perpendicular to the film. This arrangement of crystals reduced oxygenʹs tortuosity through the multilayer films. This conclusion was verified by increased oxygen permeability of the stretched–recrystallized multilayer films.