- Three types of poly (ethylene oxide)(PEO) networks cross-linked by silicone-based compounds have been formed. One type of network prepared from allyl-substituted poly (ethylene glycol)(PEG), is stable whereas the other two are degradable. The degree of swelling of the resulting hydrogels depends strongly on the PEO/silicone ratio and on temperature. From the weight fraction of soluble material in the networks, the extent of cross- linking reaction has been estimated. The molecular weight between cross-links has been calculated independently from the weight fraction of soluble material in the networks and from swelling data.