Mechanochemistry for On-Demand Polymer Network Materials

Macromolecules, Journal Year: 2025, Volume and Issue: unknown

Published: Jan. 1, 2025

Contemporary polymer network materials, such as hydrogels and elastomers, require not only enhanced mechanical properties but also adaptability during or after use. Polymer mechanochemistry, which utilizes force to induce chemical reactions within polymers, has shown great potential in meeting these demands. This Perspective will explore how mechanophores, when integrated into networks, can regulate microscale fracture pathways, either strengthening weakening the materials. Additionally, it examine force-induced bond scission trigger additional adaptively adjust structures for on-demand functions. These force-activated could lead strategies strengthening, reshaping, patterning materials through growth, or, conversely, result extensive material degradation. The highlight of tough double mechanochemical that use energy drive an efficient controllable manner. opens up new possibilities developing force-triggered "living materials" similar biological systems.

Language: Английский

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Experimental quantitation of molecular conditions responsible for flow-induced polymer mechanochemistry

Nature Chemistry, Journal Year: 2023, Volume and Issue: 15(9), P. 1214 - 1223

Published: July 10, 2023

Language: Английский

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Sacrificial Mechanical Bond is as Effective as a Sacrificial Covalent Bond in Increasing Cross-Linked Polymer Toughness

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 145(43), P. 23794 - 23801

Published: Oct. 18, 2023

Sacrificial chemical bonds have been used effectively to increase the toughness of elastomers because such dissociate at forces significantly below fracture limit primary load-bearing bonds, thereby dissipating local stress. This approach owes much its success ability adjust threshold force which sacrificial fail desired rate, for example, by selecting either covalent or noncovalent bonds. Here, we report experimental and computational evidence that a mechanical bond, responsible structural integrity rotaxane catenane, increases elastomer's strain, stress, energy as bond comparable mechanochemical dissociation kinetics. We synthesized studied 6 polyacrylates cross-linked difluorenylsuccinonitrile (DFSN), is an established mechanochromic moiety; [2]rotaxane, whose stopper allows wheel dethread on same subsecond time scale DFSN dissociates when under tensile 1.5-2 nN; structurally homologous [2]rotaxane with bulkier stable >5.5 similarly stoppered [3]rotaxanes containing in their axles; control polymer aliphatic nonsacrificial cross-links. Our data suggest dethreading without failure any may be important, hitherto unrecognized, contributor some rotaxane-cross-linked polymers provide mechanism material behavior independently response networks, due distinct relationships between structure reactivity.

Language: Английский

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Enhancing the Reactivity of Mechanically Responsive Units via Macromolecular Design

Macromolecules, Journal Year: 2024, Volume and Issue: 57(2), P. 425 - 433

Published: Jan. 3, 2024

The field of polymer mechanochemistry has experienced a rapid growth in the past two decades because establishment concept mechanophores, which describes mechanically active molecular units. A wide variety mechanophore functions have been developed, and these are expected to evolve into practical applications. In particular, self-reporting mechanochromism glassy polymers, thermoplastic elastomers, networks extensively explored. However, owing low reaction efficiency mechanophores bulk materials, induced property changes restricted optical properties. Recent studies revealed that macromolecular design contributes more substantially mechanochemical sensitivity than fine-tuning structure itself. This Perspective aims provide an overview strategies based on transfer force efficiently through chains.

Language: Английский

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Mechanochemical Approaches to Fundamental Studies in Soft‐Matter Physics

Angewandte Chemie International Edition, Journal Year: 2024, Volume and Issue: 63(19)

Published: Feb. 26, 2024

Stretching a segment of polymer beyond its contour length makes (primarily backbone) bonds more dissociatively labile, which enables mechanochemistry. Integrating some backbone into suitably designed molecular moieties yields mechanistically and kinetically diverse chemistry, is becoming increasingly exploitable. Examples include, most prominently, attempts to improve mechanical properties bulk polymers, as well prospective applications in drug delivery synthesis. This review aims highlight an emerging effort apply the concepts experimental tools mechanochemistry fundamental physical questions soft matter. A succinct summary state-of-the-knowledge field, with emphasis on foundational generalizable observations, followed by analysis 3 recent examples yielding molecular-level details elastomer failure, macromolecular chain dynamics elongational flows kinetic allostery. We conclude reasons assume that highlighted approaches are broader range problems than considered date.

Language: Английский

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Suppressive Photochromism and Promotive Mechanochromism of Rhodamine Mechanophore by the Strategy of Poly(methyl acrylate)/Polyurethane Interpenetrating Polymer Network

ACS Macro Letters, Journal Year: 2024, Volume and Issue: 13(3), P. 308 - 314

Published: Feb. 19, 2024

As molecular design and the structure–property relationships of photochemical molecules established in literature serve as a convenient reference for mechanophore exploration, many typical mechanophores suffer undesired responses to UV light or even sunlight bulk polymers. We developed strategy poly(methyl acrylate)/polyurethane (PMA/PU) interpenetrating polymer network (IPN) suppress photochromic property promote its mechanochromic property. A widely used rhodamine (Rh-2OH) was first incorporated into polyurethane (P1). Then P1 swollen methyl acrylate photopolymerized prepare PMA2.8/PU IPN (P2). Different from photo/force-responsive P1, P2 selectively responded force because low free volume greatly hinders photoisomerization spirolactam, suggesting that simple successfully resolves giant problem nonselective response photo/force mechanophores. Moreover, PMA/PU enhanced mechanical property, resulting higher mechanochemical activation ratio than PU, prestretching effect promoted sensitivity significantly. believe can be applied other mechanophores, promoting their application more complicated environments.

Language: Английский

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Spirolactam and ESIPT in a Double-Network Elastomer: Multicolor Mechanochromism and Dual-Ratiometric Strain Sensing in Low and High Tensile Stress

Macromolecules, Journal Year: 2024, Volume and Issue: 57(7), P. 3368 - 3375

Published: March 26, 2024

Monitoring strain/stress in the bulk polymer material by mechanochromic mechanophores (MMs) with multimodal analyses can provide valuable information under loading. Herein, multicolor mechanochromism from cyan to blue and further purplish red dual ratiometric strain sensing low high tensile stress were realized incorporating noncovalent bond-type excited-state intramolecular proton transfer MM PhMz-4OH covalent rhodamine Rh6G-2OH into first network of a PU–PMA (polyurethane–polymethacrylate) double-network elastomer. In situ fluorescence spectra during tests, normalized intensity enol emission increased linearly (<275% or <3.49 MPa) that rhodol (>275% >3.49 MPa), which attributed higher activation force spirolactam than disaggregation. The growth R/G due ring opening RGB could also linear stress. solvent effect on was investigated. This strategy might detailed tracking whole loading experience elastomers.

Language: Английский

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Autonomic Self-Healing of Polymers: Mechanisms, Applications, and Challenges

Molecules, Journal Year: 2025, Volume and Issue: 30(3), P. 469 - 469

Published: Jan. 22, 2025

Mechanical loads degrade polymers by enabling mechanochemical fragmentation of macromolecular backbones. In most polymers, this is irreversible, and its accumulation leads to the appearance propagation cracks and, ultimately, fracture material. Self-healing describes a diverse loosely defined collection approaches that aim at reversing damage. Most reported synthetic self-healing are non-autonomic, i.e., they require user input free energy (in form heat, irradiation, or reagents) into damaged material initiate repair. Here, we critically discuss emerging chemical autonomic rely on regenerating density load-bearing, dissociatively-inert backbone bonds either after load partially dissipated continuously in competition with mechanochemically driven loss backbones loaded We group chemistries three broad types whose analysis yields set criteria against which potential prospective approach yield practically relevant can be assessed quantitatively. Our suggests direct chain-to-chain addition mechanically unsaturated polyolefins promising strategy date achieve synchronous practical significance.

Language: Английский

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Mechanochemical Release of Fluorophores from a “Flex‐activated” Mechanophore

Angewandte Chemie International Edition, Journal Year: 2023, Volume and Issue: 62(39)

Published: Aug. 11, 2023

Optical force probes that can release force-dependent and visualized signals with minimal changes in the polymer main chains under mechanical load are highly sought after but currently limited. In this study, we introduce a flex-activated mechanophore (FA) based on Diels-Alder adduct of anthracene dimethyl acetylenedicarboxylatea exhibits turn-on mechanofluorescence. We demonstrate when FA is incorporated into networks or its crystalline state, it fluorescent anthracenes through retro-Diels-Alder mechanochemical reaction compression hydrostatic high pressure, respectively. The mechanism successfully confirmed. Furthermore, systematically modulate delivered to by varying crosslinking density applied macroscopic pressures. This modulation leads incremental increases activation, successive anthracenes, quantitative enhancement fluorescence intensity. exceptional potential as sensitive probe different bulk states highlighted, benefiting from unique mode emissive fluorophore releasing. Overall, report enriches our understanding structures functions mechanophores polymeric materials.

Language: Английский

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Mechanochemistry of Pterodactylane

Journal of the American Chemical Society, Journal Year: 2023, Volume and Issue: 146(1), P. 884 - 891

Published: Dec. 22, 2023

Pterodactylane is a [4]-ladderane with substituents on the central rung. Comparing mechanochemistry of structure when pulled from rung versus end revealed striking difference in threshold force mechanoactivation: dramatically lowered 1.9 nN to 0.7 We investigated bicyclic products formed mechanochemical activation pterodactylane experimentally and computationally, which are distinct ladderanes being activated compared pterodactylane's thermal reveal differences similarities pathways transformation. Interestingly, we also discovered presence elementary steps that accelerated or suppressed by within same reaction pterodactylane, suggesting rich manifolds multicyclic structures. rationalized greatly enhanced reactivity force-free ground state bond length be good low-cost predictor for cyclobutane-based mechanophores. These findings advance our understanding reactivities pathways, they will guide future designs mechanophores low forces facilitate their applications force-responsive materials.

Language: Английский

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