Photografting of methacrylic acid (MAA) on linear low-density polyethylene film (thickness = 30 mum) was investigated at 60degreesC in mixed solvents consisting of water and organic solvent with xanthone as the photoiniator. The organic solvents examined were acetone, methanol, tetrahydrofuran, and dioxane. A maximum percentage of grafting was observed at a certain concentration of organic solvent in the mixed solvent, depending on the nature of the organic solvent. Distribution of the grafted chains in the resultant MAA-grafted film, which was examined by scanning electron microscopy and attenuated total-reflection IR spectroscopy, was largely influenced by the use of the mixed solvent. The grafted samples swelled in the alkaline region and shrank in acidic medium, showing a pH-responsive character. The extent of the pH-responsive function was closely related to the location of grafted chains, which could be controlled by proper choice of the composition of organic solvent in the mixed solvent.