Summary: The ultrasonic irradiation of a polymer solution results in the breakage of macromolecular C? C bonds. In the presence of radical scavengers the formed macroradicals are prevented from termination reactions as combination or disproportionation. Using nitroxides as trapping agents the polymer is transformed into a macroinitiator, which can be used in controlled free‐radical polymerization to synthesize block copolymers. In this work several polymers were exposed to sonochemical degradation and terminated with various nitroxides, e.g. OH‐TEMPO and TIPNO. In a second reaction step the prepared polymer‐nitroxide‐adducts were applied as macroinitiators in controlled free‐radical polymerizations with styrene. The obtained products were mixtures of block copolymer and the corresponding homopolymers. The visco‐elastic properties were investigated by rheological analysis. A special separation technique with selective solvents was applied to determine the content of block copolymer.
Synthesis of block copolymers with sonochemically prepared macroinitiators.
