| Abstract
| - Microphase-separated structures of diblock copolymers with narrow molecular weightdistributions but with various composition distributions were investigated. Monodisperse nine parentblock copolymers composed of polystyrene and poly(2-vinylpyridine) having almost the same molecularweight but with different polystyrene volume fraction, φs, covering 0.1−0.9, were prepared. Successivelythey were blended variously to produce samples with various composition distributions but with constantaverage composition; that is, φs was kept constant at approximately 0.5. Structures from solvent-castand well-annealed films were observed through transmission electron microscopy and small-angle X-rayscattering. It has been found that the blends with wide composition distributions show periodic alternatinglamellar structure up to 1.7 in terms of Mw(S)/Mn(S), where Mw(S) and Mn(S) denote weight-average andnumber-average molecular weights of polystyrene block, respectively, and that the microdomain spacingincreases with increase of polydispersity of each block. Further, it was clarified that the blend showsmacrophase separation in between two kinds of regular microphase-separated structures if Mw(S)/ Mn(S)reaches approximately 1.8.
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