Facile Synthesis of Degradable Gels by Oxygen Cross-Linking of Polymers Including a Dienyl Group on Their Side Chain or at Chain Ends

We have demonstrated a facile method for the synthesis of a new kind of degradable gel, which is prepared by the introduction of a dienyl group into the side chains or the chain ends of conventional polymers such as poly(acrylic acid), poly(ethylene oxide), poly(2-hydroxyethyl methacrylate), and poly(vinyl alcohol) and the subsequent radical copolymerization of the diene with oxygen in the presence of a radical initiator. The obtained gels contain the polyperoxy units as the cross-linking points and readily degrade upon heating. Sorbic derivatives including epoxy and anhydride functional groups are used as reagents for the dienyl functionalization of the precursor polymers with a high efficiency. The heat of degradation of the polymer gels synthesized in this study is much smaller than that of the previously reported polyperoxides as degradable polymers and gels. This method is applied to the preparation of various kinds of polymer networks programmed for degradation after temporary use.