ALLYL ENDCAPPED POLYETHYLENE OXIDE CROSS-LINKERS AND THEIR USE IN SUPERABSORBENTS

Several new crosslinkers have been synthesized for evaluation in super absorbent polymers. These crosslinkers are allyl endcapped polyethylen e glycols (PEG) of 200, 600, and 3400 molecular weight. A branched pol yethylene oxide of 600 molecular weight, initiated with glycerin, was also synthesized as a trifunctional crosslinker. The allyl functionali ty was chosen because it is less reactive during radical polymerizatio n than acrylate crosslinkers, an attribute that was necessary to achie ve a more uniform gel network. A synthesis route was devised to make t he crosslinkers in high purity and yield. The purity of the crosslinke rs was determined by C-13 NMR, liquid chromatography, and size exclusi on chromatography. Gels that were produced with the allyl crosslinkers gave excellent soluble polymer levels and swelling characteristics. T he mechanism of incorporation of the allyl functionality was determine d to be exclusively vinyl polymerization rather than through hydrogen abstraction. This was determined using NMR spectroscopy, monitoring th e polymerization of a model system consisting of acrylic acid and ally lacetate. (C) 1997 John Wiley & Sons, Inc.