We report experimental findings of spontaneous perpendicular orientation and successive kinking of microdomains in film specimens of block copolymer by solution cast using selective solvent. These phenomena were firstly found out by our experiments. It is notable that only conducting solution cast is a straightforward and sophisticated to obtain perpendicular orientation of cylindrical and lamellar microdomains because mainly reported methods utilize application of external fields such as electric, magnetic, or temperature gradient field. The key point of this method exists in utilization of selective solvent which possesses different degrees of solubility for two respective components of block copolymer. The specimen used is a polystyrene-block-poly(ethylene-butylene)-block-polystyrene triblock copolymer and selective solvents were n-heptane, dichloromethane, and toluene, which are selectively good solvents for PEB (poly(ethylene-butylene)), PS (polystyrene), and PS, respectively. Furthermore, mixtures of n-heptane and dichloromethane were used for more precise control of the degree of selectivity. To analyze the nano structures in the as-cast and annealed specimens, transmission electron microscopy and two-dimensional small-angle X-ray scattering (2d-SAXS) measurements were conducted at room temperature. As a result, the edge-view 2d-SAXS pattern relevant to the kinking was obtained for the as-cast specimens by using toluene for the solution cast. To explain the mechanism, schematic illustrations are presented with the idea of spontaneous parallel orientation of cylinders or lamellae, and successive kinking during further solvent evaporation.
