Smectic phases in rod-coil diblock copolymers

A fluid of rod - coil diblock copolymers, modelled as wormlike chains, is treated by using self-consistent field theory. The 'rod' and 'coil' sections of each molecule are distinguished by their degrees of flexibility (or persistence lengths), but are otherwise identical. Interactions between molecules are taken to be of the excluded-volume type, described by the Onsager second-virial approximation. The theory is applied to liquid-crystalline phases which are either uniform (i.e., isotropic and nematic) or exhibit a uniaxial one-dimensional spatial variation (smectic-A). This work extends an earlier study (Duchs and Sullivan 2002 J. Phys.: Condens. Matter 14 12189) to account for the smectic-A phase at arbitrarily large values of the relative rod fraction. The smectic phase is found to have a partial bilayer morphology, exhibiting nearly complete interdigitation of the rod-like sections and little interdigitation of the coil sections.