Photografting of methacrylic acid (MAA) on low-density polyethylene film (thickness = 30 on), on which xanthone photoinitiator was coated earlier, in the presence of polyfunctional monomers such as N,N'-methylenebisacrylamide, ethylene glycol dimethacrylate, and trimethylol propane triacrylate was examined at 60 degrees C in water/ acetone (3:1 v/v) mixture solvent. The photografting was retarded at the earlier stage of polymerization, and then accelerated when small amounts of the polyfunctional monomers (1-3 mol % of MAA monomer used) were added to the system. Addition of the polyfunctional monomers did not affect distribution of the grafted chains in the cross section of the resultant MAA-grafted PE film, which was measured by electron probe microanalysis. The MAA-grafted samples were subjected to adsorption of cupric ions at 25 degrees C for 24 h in the system of pH = 5. The adsorption was considerably suppressed for the grafted samples prepared at the earlier stage of polymerization in the system with the polyfunctional monomers. The phenomenon was discussed in terms of the formation of crosslinked and branched structures in the MAA-grafted chains depending on the polymerization stage in the system with polyfunctional monomers. (c) 2006 Wiley Periodicals, Inc.