We established a preparation method of brush-on-brush copolymers by grafting from photoinduced ATRP of multifunctional polystyrene having N,N-diethyldithiocarbamate (DC) pendant groups with stearyl methacrylate (STM). We studied the solution properties of brush-on-brush copolymers from the view point of crowding effect of PSTM brush side chains. It was speculated from angular dependence on dynamic light scattering (DLS) that the brush-on-brush copolymer (BB1:PSTM brushes were grafted at regular intervals of 1/4 styrene units on the backbone) with large aspect ratio took a geometrical anisotropic conformation such as a cylinder due to crowding of brush side chains. In fact, transmission electron microscopy (TEM) photograph of such brush-on-brush showed a rigid rod-like morphology. (C) 2008 Elsevier Inc. All rights reserved.