Nucleation and growth of anisotropic grain in block copolymers near order-disorder transition

Ordering processes of a nearly symmetric block copolymer of polystyrene-block-polyisoprene quenched from the disordered state to the ordered state very close to the order-disorder transition temperature were lamellae developed in a disordered matrix and the shape of the grain was anisotropic, whose size along the lamellar normals is much larger than that parallel to the lamellar interfaces. This property was confirmed by the computer simulation of a phenomenological model.