Macrolattice structure of a block copolymer in a selective solvent

Macrolattice structure in the ordered phase of a poly(styrene-b-butadiene-b-styrene) (SBS, with the bulk morphology of spherical polystyrene microdomains in the polybutadiene matrix) dissolved in a selective solvent (dodecyl methacrylate, C₁₂MA, or a 75/25 w/w mixture of C₁₂MA and butylene diacrylate, BDA) which mixes preferentially with the polybutadiene matrix was examined by means of transmission electron microscopy. The use of C₁₂MA/BDA mixture as the selective solvent provided the opportunity of freezing the macrolattice structure upon UV-initiated polymerization of the acrylic monomers when the SBS content is above ca. 60 wt%. Results indicated clearly a body-centered cubic structure, in contrast to the simple cubic packing previously proposed.