Microphase-separated structure of two-component block copolymers with composition distribution

Segment distribution of component polymer in a lamellar microdomain for two-component triblock copolymer of styrene and 2-vinylpyridine with wide composition distribution was investigated by using neutron reflectivity measurement. The wide composition distribution was produced by mixing three triblock copolymers, synthesized by an anionic polymerization method, with the same molecular weight but different volume fraction of middle block chain, about 0.2, 0.5 and 0.8. The prepared triblock copolymer blends formed a uniform lamellar structure highly oriented along the direction parallel to the film surface. Also, it was clarified that the segments of the shortest middle block chain in the blend system still exist at the center of lamellar microdomain.