4-Substituted styrenes (substituent: methoxy, methyl, acetoxy, maleimido and none), were cationically polymerized with an initiator system involving poly(p-maleimidostyrene)(PMS) as a macroinitiator, having highly reactive pendent maleimide moieties and a cc-chlorobenzyl structure at the polymer end. Using PMS/SnCl4/tetra-n-butylammmonium chloride initiator system, block copolymers of 4-substituted styrenes onto PMS were obtained in CH2Cl2 at 0 degrees C. As for the polymerization of N-(4-vinylphenyl) maleimide and 4-acetoxystyrene, especially, PMS as the macroinitiator was almost completely utilized for initiation reaction and the polymers having PMS-b-poly(4-substituted styrene) platform with very narrow and unimodal molecular weight distribution were formed in contrast with the case of using 4-methoxystyrene and 4-methylstyrene with stronger electron releasing groups, in which the molecular weight distributions of the formed polymeric materials appeared to be bimodal. (C) 2010 Elsevier Ltd. All rights reserved.