The apparent mechanochemical scission rate constants kapp were then measured by sonicating the three carbamoyloxime derivative polymers at five different Mn each in duplicate in dilute THF solutions using pulsed ultrasonication (1 s on, 1 s off, 2 to 8 °C, 30% amplitude, power intensity IP = 7.4 W•cm -2 , Table and). Gel permeation chromatography (GPC) measurements before and after each sonication allowed to plot kapp against the initial molar mass Mn,start (Figure and Table ,5). kapp were determined from the time-dependent attenuation of the GPC refractive index (RI) signal corresponding to the initial polymer peak using the initial rates method. This method was selected since the respective product formation was minimally affected by competing pathways (e.g., non-selective or secondary scission) in the early stages of ultrasonication. These experiments unambiguously established the mechanophore character of the carbamoylketoximes and proved the reactivity trend TKO>MKO>AO predicted by COGEF simulations.