Polystyrene (PS)/poly(ethylene oxide) (PEO) prototype brushes were prepared by alternating free-radical copolymerization of methacryloyl-terminated PS and alpha-vinylbenzyl-omega-hydroxy or alpha-vinylbenzyl-omega-perfluoroalkyl (R-f) PEO macromonomers with the addition of Lewis acid (SnCl,). It was found from their dilute-solution properties that PS/PEO end-capped with R-f (PBRf), and PS/PEO having OH groups at terminal ends (PBOH) prototype brushes formed a single molecule in benzene and aggregates in chloroform, respectively. However, the brush PBOH formed a single molecule in N,N-dimethylformamide. Such aggregation behaviors seemed to be caused by the interaction between hydroxy groups of PEO chain ends. The brush PBOH was also converted into PBRf-type brush by chemical modification, using corresponding acid chloride. The substitution of Rf groups was similar to 70% due to slipping of terminal hydroxy groups into PEO internal domains. (c) 2006 Wiley Periodicals, Inc.