Polydisperse (Mw/Mn = 2.4) rod-coil, multi-block poly(polymethylphenylsilane-block-polyisoprene) (PMPS-b-PI), containing semiconductor segments, was characterised using atomic force microscopy (AFM) and neutron scattering. Despite high polydispersities (Mw/Mn (PMPS) = 1.64; Mw/Mn (PI) = 1.34) resulting in disorder, solid-state PMPS-b-PI was indicated to form a regular, modulated morphology with average domain repeat unit of 18.8 nm at the surface (AFM) and 18.6nm in the bulk (neutron). The observed regularity was tentatively proposed to result from a lamella-like morphology preferred by rod-coil, multi-block copolymers and the helical, segmental geometry of PMPS. This tentative theory was corroborated by good agreement between expected and found domain sizes, which indicated that copolymers did not, to a recognisable extent, fold and reverse direction. © 2003 Elsevier B.V. All rights reserved.