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We report a novel and versatile approach to achieving swelling‐induced mechanochemistry using a multinetwork (MN) strategy that enables polymer networks to repeatedly swell with monomers and solvents. The isotropic expansion of the first network (FN) provides sufficient force to drive the mechanochemical scission of a radical‐based mechanophore, difluorenylsuccinonitrile (DFSN). Although prompt recombination generally occurs in such highly mobile environments, the resulting pink radicals are kinetically stabilized in the gels, probably due to limited diffusion in the extended polymer chains. Moreover, the DFSN embedded in the isotropically strained chain exhibits increased thermal reactivity, which can be reasonably explained by an entropic contribution of the FN to the dissociation. The utility of the MN polymers is demonstrated not only in terms of swelling‐force‐induced network modification, but also in the context of tunable reactivity of the dissociative unit through proper design of the hierarchical network architecture. [ABSTRACT FROM AUTHOR]

Mechanochromic elastomers that exhibit force‐induced cross‐linking reactions in the bulk state are introduced. The synthesis of segmented polyurethanes (SPUs) that contain difluorenylsuccinonitrile (DFSN) moieties in the main chain and methacryloyl groups in the side chains was carried out. DFSN was selected as the mechanophore because it dissociates under mechanical stimuli to form pink cyanofluorene (CF) radicals, which can also initiate the radical polymerization of methacrylate monomers. The obtained elastomers generated CF radicals and changed color by compression or extension; they also became insoluble due to the mechanically induced cross‐linking reactions. Additionally, an SPU containing diphenylmethane units also exhibited highly sensitive mechanofluorescence. To the best of our knowledge, this is the first report to demonstrate damage detection ability and changes in the mechanical properties of bulk elastomers induced by simple compression or extension. [ABSTRACT FROM AUTHOR]

Mechanochromic dendrimers (MDs) were developed as an ideal model for the elucidation of the relationship between the primary structure of molecules/macromolecules with a mechanophore. We discovered that the ratio of activated mechanophores, i.e., the performance parameter to quantitatively evaluate the mechanical response, drastically increases in higher-generation dendrimers. [ABSTRACT FROM AUTHOR]

Keywords: Chromophores; Gels; Mechanochemistry; Polymers; Radicals EN Chromophores Gels Mechanochemistry Polymers Radicals 1 1 1 02/21/23 20230220 NES 230220 B The swelling force b exerted by solvents in polymer gels is revealed to trigger mechanochemical reactions, as reported by Takuma Watabe and Hideyuki Otsuka in their Research Article (e202216469). Chromophores, Gels, Mechanochemistry, Polymers, Radicals A multinetwork strategy based on sequential monomer swelling and polymerization processes makes the original network sensitive to mechanical stimuli. [Extracted from the article]

Chromophores, Gels, Mechanochemistry, Polymers, Radicals A multinetwork strategy based on sequential monomer swelling and polymerization processes makes the original network sensitive to mechanical stimuli. Keywords: Chromophores; Gels; Mechanochemistry; Polymers; Radicals EN Chromophores Gels Mechanochemistry Polymers Radicals 1 1 1 02/21/23 20230220 NES 230220 B The swelling force b exerted by solvents in polymer gels is revealed to trigger mechanochemical reactions, as reported by Takuma Watabe and Hideyuki Otsuka in their Research Article (e202216469). [Extracted from the article]

Electron paramagnetic resonance, mechanochromism, polymer mechanochemistry, polyurethanes, self-strengthening Innenrücktitelbild: Segmented Polyurethane Elastomers with Mechanochromic and Self-Strengthening Functions (Angew. Keywords: electron paramagnetic resonance; mechanochromism; polymer mechanochemistry; polyurethanes; self-strengthening EN electron paramagnetic resonance mechanochromism polymer mechanochemistry polyurethanes self-strengthening 8639 8639 1 04/01/21 20210406 NES 210406 B Mechanofunktionelle Polymere b , die einen Farbwechsel, Fluoreszenz und die Fähigkeit zur Selbstverfestigung aufweisen, werden von Hideyuki Otsuka et al. in ihrer Zuschrift auf S. 8487 vorgestellt. [Extracted from the article]

Keywords: electron paramagnetic resonance; mechanochromism; polymer mechanochemistry; polyurethanes; self-strengthening EN electron paramagnetic resonance mechanochromism polymer mechanochemistry polyurethanes self-strengthening 8555 8555 1 04/01/21 20210406 NES 210406 B Mechanofunctional polymers b that exhibit color change, fluorescence, and self-strengthening ability were developed by Hideyuki Otsuka et al. in their Communication on page 8406. Electron paramagnetic resonance, mechanochromism, polymer mechanochemistry, polyurethanes, self-strengthening Inside Back Cover: Segmented Polyurethane Elastomers with Mechanochromic and Self-Strengthening Functions (Angew. [Extracted from the article]