Triblock copolymers containing central poly(ethylene oxide) blocks and polyglycidol side chains were synthesized using cesium polyoxyethylene glycolates as macroinitiators. Water soluble copolymers containing central blocks of 40 to 230 structural poly(ethylene oxide) units and side chains of 30 to 70 polyglycidol units and relatively narrow molecular weight distribution were obtained. The copolymers were crosslinked with glutar aldehyde and their swelling in water and methanol was investigated.