Atom transfer radical polymerization (ATRP) of dimethyl(methacryloyloxy)methyl phosphonate (MAC(1)P) was investigated in toluene, in the presence of methyl 2-bromoisobutyrate as the initiator, and using different metal and ligand systems. Polymerization proceeded with very low monomer conversion, which was attributed to the ability of phosphorus to complex the copper ions, removing copper ions from original ligand, and then stopping the MAC(1)P polymerization. Poly(MMA)-b-poly(phosphonate acrylate) diblock copolymer structure was efficiently obtained by the ATRP process, based on a four-step reaction. Poly(MMA)-b-poly(tert-butyl acrylate) diblock copolymer was first obtained by ATRP, then the tert-butyl groups were removed and phosphonate functions were incorporated by esterification reaction, using 4-dimethylaminopyridine as the catalyst. This new diblock copolymer Was used as an additive for anticorrosive coating; however, no improvement (using the salt spray test technique) was observed comparatively with the statistical copolymer with the same acid content. This study enhanced that the acid content of phosphonic additives is the main parameter, unlike their structuration, to increase the resistance to corrosion. (C) 2009 Wiley Periodicals, Inc. J Appl Polym Sci 114: 2213-2220, 2009