SYNTHESIS OF STAR-SHAPED POLYMERS VIA COORDINATION OF BIPYRIDYL-TERMINATED POLYOXYETHYLENE WITH METAL-IONS

This paper describes the synthesis of various star-shaped polymers by means of complexation of bipyridyl-terminated polyoxyethylene with Ru( II) ion. Three kinds of bipyridyl-terminated polyoxyethylenes of diffe rent molecular weights were prepared from the corresponding polyoxyeth ylene monomethyl ethers with narrow molecular weight distributions. Bi pyridyl was found to be introduced quantitatively at the end of the po lymers based on the results of UV spectra. The formation of a starshap ed polymer was carried out by the reaction of RuCl3 with three equival ents of bipyridyl-terminated polyoxyethylene. The UV spectrum of the s tar-shaped polymer obtained supported the formation of a typical Ru(II ) tris(bipyridyl) complex. From the results of GPC, the starshaped pol ymer obtained had a higher molecular weight than the prepolymer and sh owed a narrow molecular weight distribution. In the case of a Ni(II) o r a Co(II) complex, however, the star-shaped polymer was found to be d issociated into three linear prepolymers under the conditions of GPC m easurement.