An Investigation of the Selective Chain Scission at Centered Diels–Alder Mechanophore under Ultrasonication

Abstract

It is a challenging topic to disconnect a linear polymer selectively at the mechanophore site by an external force in a “cold” fashion. In this work, the effect of the power output of ultrasonication on the selective cleavage at the centered urfuryl-maleimide Diels–Alder (DA) mechanophore of poly(methyl acrylate)s (DA-PMA-a and DA-PMA-b) were quantitatively investigated by comparative study on experimental and simulated chain scission kinetics as well as high-resolution 1H NMR spectroscopy (600 MHz). At low power output of the ultrasonication (2.10 W), DA-PMA-a with Mn of ca. 2Mlim (Mlim, below which no further chain scission was observed) presented a DI (degradation index)−t (sonication time) plot with a turnover point at ca. 1.0 and no clear variation of the molecular weight after the turnover, which met well with the calculated center cleavage mode. At 5.52 W, DA-PMA-a and a poly(methyl acrylate) that contained two centered ester bonds (ester-PMA) presented similar DI–t plots with turnover points less ...