Atom transfer radical polymerization (ATRP) was applied to a novel synthesis of prototype copolymer brushes. The procedure included the following steps: (1) free-radical copolymerization of vinylbenzyl-terminated polystyrene (PS-VB) macromonomer and N-(4-hydroxyphenyl)maleimide gave well-defined alternating comb-shaped copolymers, (2) subsequent esterification reaction [N-(4-hydroxyphenyl)maleimide sites] of such comb-shaped copolymer with 2-bromoisobutyryl bromide yielded a comb-shaped polyinitiator, and (3) the grafting-from ATRP method of methyl methacrylate (MMA) using comb-shaped polyinitiator provided PS/poly(methyl methacrylate) (PMMA) alternating copolymer brushes. Dilute solution properties and morphological results of both comb-shaped polyinitiator and prototype copolymer brushes were investigated by static and dynamic light scattering and transmission electron microscopy. As a result, prototype copolymer brush composed of short aspect ratio changed the shape from ellipsoid to starlike conformation because both polystyrene (PS) and PMMA side chains were stretched by introduction of PMMA grafted chains.