Fig. 5: US-triggered flex-activation of mechanophores in PMBs.
From: Polymer microbubbles as universal platform to accelerate polymer mechanochemistry
a Schematic illustration. b Optical micrograph of PMB-Flex, scale bar: 50 µm. The experiment was repeated three times, and similar images were obtained. c Fluorophore (N1-A3) release from PMB-Flex under 20 kHz US irradiation. Data are presented as mean values +/− the standard deviation. N = 3 independent sonications. d 1H NMR (400 MHz) spectra of free N1-A3 and released N1-A3. e Fluorophore release from PMB-Flex under 0.68 MHz US irradiation. Inset: photographs of PMBs before (left) and after (right) HIFU treatment under daylight (top) and 365 nm UV (bottom) illumination in MeCN/H2O. Data are presented as mean values +/− the standard deviation. N = 3 independent sonications. f Fluorescence spectra of microgel suspension after 5 min US irradiation. g Force-distance curves of PMB-Flex and microgels obtained by AFM, scale bar: 50 µm. h Stiffnesses of PMB-Flex and microgels obtained from panel g. i Molecular structure that was used in computational modelling to investigate the flex activation. j Activation energy VA in dependence of the applied pulling force. k Activation energy VA in dependence of the force constant of the applied uniaxial pressure.
