A technique is described for the preparation of arborescent graft copolymers containing poly(tert-butyl methacrylate) (PtBMA) segments. For this purpose, tert-butyl methacrylate is first polymerized with 1,1-diphenyl-2-methylpentyllithium in tetrahydrofuran. The graft copolymers are obtained by addition of a solution of a bromomethylated polystyrene substrate to the living PtBMA macroanion solution. Copolymers incorporating either short (M-w approximate to 5000) or long (M-w approximate to 30,000) PtBMA side chains were prepared by grafting onto linear, comb-branched (GO), G1, and G2 bromomethylated arborescent polystyrenes. Branching functionalities ranging from 9 to 4500 and molecular weights ranging from 8.8 X 10(4) to 6.3 X 10(7) were obtained for the copolymers, while maintaining a low apparent polydispersity index (M-w/M-n approximate to 1.14-1.25). Arboreseent polystyrene-graft-poly(methacrylic acid) (PMAA) copolymers were obtained by hydrolysis of the tert-butyl methacrylate units. Dynamic light scattering measurements showed that the arborescent PMAA copolymers are more expanded than their linear PMAA analogues when neutralized with NaOH. This effect is attributed to the higher charge density in the branched arborescent copolymer structures. (C) 2008 Wiley Periodicals, Inc.