Nano-Periodic Arrangement of Structural Phases of Polyethylene-block-Polystyrene Copolymer as Induced by Orientation Techniques

摘要

Shear flow and tensile drawing are often applied to the directional arrangement of separated phases of block copolymer, where a unique transition from the initial lamellar stacking to a deformed-chevron morphology has been reported for polystyrene (PS)-block-polyisoprene copolymer. However, the orientation of the separated phases easily relaxes after the applied tensile force is released, due to the rubbery characteristics of this copolymer. Therefore, it is difficult to obtain a highly oriented morphology for this copolymer. In order to fix the morphological orientation induced by the tensile force, Sakurai et al. introduced cross-linking into the copolymer chains after tensile deformation. Crystallization is also utilized to restrict the relaxation of the oriented morphology after deformation. Loo et al. oriented the cylinder morphology of the polyethylene (PE)-block-PS copolymer by shear flow during melt-extrusion through a channel die. The orientation along the extrusion axis could be locked by oriented crystallization of the PE block.