Mechanochromic dendrimers: the relationship between primary structure and mechanochromic properties in the bulk

Watabe, Takuma; Ishizuki, Kuniaki; Aoki, Daisuke; Otsuka, Hideyuki

doi:10.1039/c9cc03011e

Cited by 44 publications

(49 citation statements)

References 49 publications

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“…In solution under ultrasonication, single mechanophores at the center of the main chain are more likely to be activated in polymers with high molecular length 45 , 46 . On the other hand, in the bulk state under exposure to grinding, the mechano-responsiveness of mechanochromophores, especially radical-type mechanophores such as TASN, is governed by both the molecular weight and the number of branches 47 , 48 . The insights into mechano-responsiveness in polymer crystallization obtained in this paper are expected to broaden the understanding of polymer mechanochemistry.…”

Section: Resultsmentioning

confidence: 99%

Crystallization-induced mechanofluorescence for visualization of polymer crystallization

et al. 2021

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The growth of lamellar crystals has been studied in particular for spherulites in polymeric materials. Even though such spherulitic structures and their growth are of crucial importance for the mechanical and optical properties of the resulting polymeric materials, several issues regarding the residual stress remain unresolved in the wider context of crystal growth. To gain further insight into micro-mechanical forces during the crystallization process of lamellar crystals in polymeric materials, herein, we introduce tetraarylsuccinonitrile (TASN), which generates relatively stable radicals with yellow fluorescence upon homolytic cleavage at the central C–C bond in response to mechanical stress, into crystalline polymers. The obtained crystalline polymers with TASN at the center of the polymer chain allow not only to visualize the stress arising from micro-mechanical forces during polymer crystallization via fluorescence microscopy but also to evaluate the micro-mechanical forces upon growing polymer lamellar crystals by electron paramagnetic resonance, which is able to detect the radicals generated during polymer crystallization.

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Section: Resultsmentioning

confidence: 99%

Crystallization-induced mechanofluorescence for visualization of polymer crystallization

et al. 2021

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“…[16,17] Va rious design principles influence mechanochemical reactivity including the location of mechanophores, [18] regio-and stereochemistry, [19][20][21][22][23] linkers, [24][25][26] polymer composition, [27,28] and polymer topology. [29] In regard to topology,i ntramolecularly cross-linked, [30][31][32][33][34] cyclic, [35] dendritic, [36,37] star, [38][39][40][41][42][43] bottlebrush, [44][45][46] and dendronized polymers, [47] have been utilized to tune mechanochemical reaction kinetics and/or mechanophore activation efficiency. Them ajority of these topology studies have been conducted using ultrasonication (US) or, to alesser extent, ball-mill grinding (BMG).…”

Section: Introductionmentioning

confidence: 99%

Mechanochemical Reactivity of Bottlebrush and Dendronized Polymers: Solid vs. Solution States

2021

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We explored the mechanochemical degradation of bottlebrush and dendronized polymers in solution (with ultrasonication, US) and solid states (with ball-mill grinding, BMG). Over 50 polymers were prepared with varying backbone length and arm architecture,composition, and size.With US,w ef ound that bottlebrush and dendronized polymers exhibited consistent backbone scission behavior,w hichw as related to their elongated conformations in solution. Considerably different behavior was observed with BMG,a sa rm architecture and composition had as ignificant impact on backbone scission rates.A rm scission was also observed for bottlebrush polymers in both solution and solid states,but only in the solid state for dendronized polymers.Motivated by these results,m ulti-mechanophore polymers with bottlebrush and dendronized polymer architectures were prepared and their reactivity was compared. Although dendronized polymers showed slower arm-scission, the selectivity for mechanophore activation was muchh igher.O verall, these results have important implications to the development of new mechanoresponsive materials.

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“…[ 2 ] Various chemical stress‐quantification‐tools have been demonstrated by so‐called mechanophores including stress‐induced chemiluminescence, [ 3–5 ] the release of small molecules [ 6–9 ] and direct mechanochromic indicators. [ 10–18 ] Alternatively, the induction of catalytic reactions based on the decoupling metal–ligand complexes by mechanical stimuli is used. [ 19–26 ] The most commonly used mechanochromic polymers are based on spiropyranes, [ 16,18 ] able to generate a merocyanine chromophores upon mechanical activation depending on their substitution pattern.…”

Section: Figurementioning

confidence: 99%

“…[2] Various chemical stress-quantificationtools have been demonstrated by so-called mechanophores including stress-induced chemiluminescence, [3][4][5] the release of small molecules [6][7][8][9] and direct mechanochromic indicators. [10][11][12][13][14][15][16][17][18] Alternatively, the induction of catalytic reactions based on the decoupling metal-ligand complexes by mechanical stimuli is used. [19][20][21][22][23][24][25][26] The most commonly used mechanochromic polymers (M w = 1800 Da) to yield the 1-methylimidazolium bromide functionalized chains, followed by conversion of the 1-methylimidazole-chains to the respective copper(I)-bis(NHC)-mechanophores with Cu 2 O-powder (5 µm).…”

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confidence: 99%

Multicomponent Stress‐Sensing Composites Fabricated by 3D‐Printing Methodologies

Rupp

Binder

2020

Macromol. Rapid Commun.

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The preparation and characterization of mechanoresponsive, 3D‐printed composites are reported using a dual‐printing setup for both, liquid dispensing and fused‐deposition‐modeling. The here reported stress‐sensing materials are based on high‐ and low molecular weight mechanophores, including poly(ε‐caprolactone)‐, polyurethane‐, and alkyl(C11)‐based latent copper(I)bis(N‐heterocyclic carbenes), which can be activated by compression to trigger a fluorogenic, copper(I)‐catalyzed azide/alkyne “click”‐reaction of an azide‐functionalized fluorescent dye inside a bulk polymeric material. Focus is placed on the printability and postprinting activity of the latent mechanophores and the fluorogenic “click”‐components. The multicomponent specimen containing both, azide and alkyne, are manufactured via a 3D‐printer to place the components separately inside the specimen into void spaces generated during the FDM‐process, which subsequently are filled with liquids using a separate liquid dispenser, located within the same 3D‐printing system. The low‐molecular weight mechanophores bearing the alkyl‐C11 chains display the best printability, yielding a mechanochemical response after the 3D‐printing process.

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Mechanochromic dendrimers: the relationship between primary structure and mechanochromic properties in the bulk

Abstract: Radical-type mechanochromic dendrimers were developed and their mechano-responsivity drastically increased in higher-generation dendrimers.

Cited by 44 publications

References 49 publications

Crystallization-induced mechanofluorescence for visualization of polymer crystallization

Crystallization-induced mechanofluorescence for visualization of polymer crystallization

Mechanochemical Reactivity of Bottlebrush and Dendronized Polymers: Solid vs. Solution States

Multicomponent Stress‐Sensing Composites Fabricated by 3D‐Printing Methodologies

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