Method for fractioning poly (ethylene oxide) formed using a metallic cyanide catalyst

This invention relates to methods for purifying poly(ethylene oxide) polymers. A poly(ethylene oxide) polymer having low and high molecular weight fractions is fractionated by dissolving the polymer in a solvent for the low molecular weight fraction. A good separation of the low and high molecular weight fractions can be obtained. When the poly(ethylene oxide) polymer contains a metal cyanide catalyst, this process also provides a good separation of the catalyst from the low molecular weight fraction. In this instance, the catalyst remains active and the high molecular weight fraction containing the catalyst can be recycled into subsequent polymerization processes.