Further, we systematically compared the activation rates of chain-centered mechanophores through solution-phase ultrasonication experiments. Ultrasound acoustic field causes pressure variation in the solution and generates rapidly collapsing cavitation, inducing a solvodynamic shear force field that transduces force to mechanophores covalently embedded in the backbone of dissolved polymers. Force is maximized at the midpoint of the polymer chain, and longer chains experience greater force. Rates of mechanophore conversion in ultrasonication experiments are frequently used as a measure to assess the relative reactivities among different mechanophores. We synthesized PMA1-PMA3 containing chain-centered mechanophores M1-M3 by tethering bis-functionalized mechanophores to identical azide-functionalized poly(methyl acrylate) polymers (PMA-Azide, Mn NMR = 34.7 kg/mol) through CuAAC click chemistry (Figure and SI). This method guarantees uniform chain lengths for PMA1-PMA3, ensuring that all chain-centered mechanophores experience similar force environments under standard ultrasonication treatments. Solvodynamic force converts the photoinert parallel diarylethenes to their photoswitchable antiparallel diastereomers, as illustrated by the sonication-dependent photoactivity of PMA3 (Figure ). A solution of PMA3 (15 mL, 1.0 mg/mL in acetonitrile) was initially colorless and remained colorless after UV exposure. In contrast, UV irradiation (λ = 365 nm) turned the ultrasound-activated polymer sample into a red color, with an absorption peak emerging at around 530 nm. Moreover, the ultrasonicated PMA3 solution could be switched between the colored and colorless forms reversibly under UV and visible irradiation, matching our previous findings. We observed minimal fatigue after six cycles of UV irradiation at 365 nm and four cycles at 254 nm (Figure ). PMA1 and PMA2 exhibit similar sonication-dependent photochromic properties (Supporting Information Section 4 and Section 5).