Photografting of methacrylic acid on polyethylene film: Effect of mixed solvents consisting of water and organic solvent

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. (C) 2002 John Wiley Sons, Inc.