Combination of Mechanochemical Degradation of Polymers with Controlled Free-Radical Polymerization

The result of ultrasound on polymer solutions is the breakage of macromolecular CC-bonds due to cavitation. The fact that termination reactions of mechanoradicals as disproportionation and combination are suppressed in the presence of radical scavengers makes the following method possible. Thus the use of nitroxides acting as chain-terminating agents allows the creation of macroinitiators which can be used in controlled free-radical polymerization. In this work, we investigate the mechanochemical degradation of poly(methyl methacrylate) (PMMA) in the presence of OH-TEMPO and the application of the irradiated polymers as macroinitiators in a controlled radical polymerization. The content of OH-TEMPO terminated chains in the degraded product is determined by a computer-aided procedure on the basis of molecular weight distributions. Ultrasonic degradation of PMMA, decrease of molar mass (Mn), and polydispersity (Pd) as a function of irradiation time, power output = 200 W, ϑ = 45–50 °C.