PEO-AN block copolymers were synthesized in aqueous solution by using ultrasonic technique. The polymerization of AN was initiated by macroradicals produced during ultrasonic degradation of PEO. The rate of reaction was proportional to AN concentration
and the amount of AN copolymerized with per mole of PEO increased with the degradation rate constant of PEO. And the structure of the copolymers was identified by lelementary analysis