A self-repairing, supramolecular polymer system: healability as a consequence of donor–acceptor π–π stacking interactions

Burattini, Stefano; Colquhoun, Howard M.; Fox, Justin D.; Friedmann, Donia; Greenland, Barnaby W.; Harris, Peter; Hayes, Wayne; Mackay, Michael E.; Rowan, Stuart J.

doi:10.1039/b910648k

Cited by 504 publications

(274 citation statements)

References 31 publications

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“…Because the rates of the final two steps are inversely proportional to the molecular mass, healing is generally slow and inefficient. This problem can be overcome by exploiting thermally reversible, covalent bonds 7,8 or non-covalent supramolecular motifs 5,9,10 that allow the reaction equilibrium to be temporarily shifted to lower-molecular-mass species 11 on exposure to heat. This reduces the viscosity of the material, such that defects can be mended, before the equilibrium is shifted back and the polymer is reformed.…”

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confidence: 99%

Optically healable supramolecular polymers

Burnworth

Tang

Kumpfer

et al. 2011

Nature

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Polymers with the ability to repair themselves after sustaining damage could extend the lifetimes of materials used in many applications 1 . Most approaches to healable materials require heating the damaged area [2][3][4] . Here we present metallosupramolecular polymers that can be mended through exposure to light. They consist of telechelic, rubbery, low-molecular-mass polymers with ligand end groups that are non-covalently linked through metal-ion binding. On exposure to ultraviolet light, the metal-ligand motifs are electronically excited and the absorbed energy is converted into heat. This causes temporary disengagement of the metal-ligand motifs and a concomitant reversible decrease in the polymers' molecular mass and viscosity 5 , thereby allowing quick and efficient defect healing. Light can be applied locally to a damage site, so objects can in principle be healed under load. We anticipate that this approach to healable materials, based on supramolecular polymers and a light-heat conversion step, can be applied to a wide range of supramolecular materials that use different chemistries.The healing of cracks in amorphous polymers by heating above the glass transition temperature (T g ) involves surface rearrangement and approach of polymer chains, followed by wetting, diffusion and reentanglement of the chains 6 . Because the rates of the final two steps are inversely proportional to the molecular mass, healing is generally slow and inefficient. This problem can be overcome by exploiting thermally reversible, covalent bonds 7,8 or non-covalent supramolecular motifs 5,9,10 that allow the reaction equilibrium to be temporarily shifted to lower-molecular-mass species 11 on exposure to heat. This reduces the viscosity of the material, such that defects can be mended, before the equilibrium is shifted back and the polymer is reformed. Supramolecular polymers that phase separate into physically crosslinked networks (Fig. 1a) should be especially well suited for this purpose, because such morphologies generally bestow the material with high toughness. The supramolecular motifs can disengage in the solid state on exposure to heat or a competitive binding agent 12,13 , causing disassembly into small molecules 14 and viscosity reductions. Reporting a series of supramolecular materials formed by metal-ligand interactions, we demonstrate here that this architecture is an excellent basis for elastomeric materials in which defects can be efficiently repaired. We show that the use of light 15 as a stimulus for the dissociation of supramolecular motifs has distinct advantages over thermally healable systems, including the possibility of exclusively exposing and healing the damaged region.The new polymers are based on a macromonomer comprising a rubbery, amorphous poly(ethylene-co-butylene) core with 2,6-bis(19-methylbenzimidazolyl)pyridine (Mebip) ligands at the termini (Fig. 1b, 3). This design was based on the assumption that the hydrophobic core and the polar metal-ligand motif would phase separate 16 . Metal-Mebip com...

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mentioning

confidence: 99%

Optically healable supramolecular polymers

Burnworth

Tang

Kumpfer

et al. 2011

Nature

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1,633

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“…Mechanically responsive π-π interactions have also been utilized in supramolecular polymers, where π-π stacking between electronically complementary (i.e., electron-rich and electron-poor) π-conjugated groups has been utilized to achieve supramolecular polymerization. [60][61][62][63] For example, pairs of naphthalene diimide groups that were introduced into the backbone and termini of polymer P1 ( Figure 13) bind to pyrene moieties that were introduced to both ends of polymer P2. Combination of P1 and P2 leads to the formation of a supramolecular network structure, in which cross-links are based on intermolecular interactions between electron donor and acceptor groups.…”

Section: π-π Interactionsmentioning

confidence: 99%

“…Combination of P1 and P2 leads to the formation of a supramolecular network structure, in which cross-links are based on intermolecular interactions between electron donor and acceptor groups. [61] The formation of donor-acceptor stacked structures is not only evidenced through the material's mechanical properties, but can also be inferred from the appearance of a characteristic reddish color, which arises from the naphthalene diimide / pyrene charge transfer interactions. The materials system at hand was designed to be healable after being damaged.…”

Section: π-π Interactionsmentioning

confidence: 99%

Mechanochemistry in Polymers with Supramolecular Mechanophores

Haehnel

Sagara

Simon

et al. 2015

Topics in Current Chemistry

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“…Previous research suggests that hydrogen bond and π -π stacking can be introduced to polymer to form noncovalent interaction among polymer chains [6][7][8][9], and those non-covalent interactions present significant temperature sensitivity, which shows rich transitions at narrow temperature and frequency range. Therefore, those materials offer a unique chance to investigate the transitions of polymers, especially the effect of those transitions on stress-strain behaviour, at narrow temperature and/or frequency regime compared with traditional polymers such as polycarbonate and poly(methyl metacrylate) etc., which normally need large temperature and frequency range to observe those transitions [10][11][12].…”

Section: Chemical Structure Of Spumentioning

confidence: 99%

Effect of temperature and strain rate on the compressive behaviour of supramolecular polyurethane

Tang

Siviour

Buckley

et al. 2015

EPJ Web of Conferences

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Abstract. Supramolecular polyurethanes (SPUs) possess thermoresponsive and thermoreversible properties, and those characteristics are highly desirable in both bulk commodity and value-added applications such as adhesives, shape-memory materials, healable coatings and lightweight, impact-resistant structures (e.g. protection for mobile electronics). A better understanding of the mechanical properties, especially the rate and temperature sensitivity, of these materials are required to assess their suitability for different applications. In this paper, a newly developed SPU with tuneable thermal properties was studied, and the response of this SPU to compressive loading over strain rates from 10 −3 to 10 4 s −1 was presented. Furthermore, the effect of temperature on the mechanical response was also demonstrated. The sample was tested using an Instron mechanical testing machine for quasi-static loading, a home-made hydraulic system for moderate rates and a traditional split Hopkinson pressure bars (SHPBs) for high strain rates. Results showed that the compression stress-strain behaviour was affected significantly by the thermoresponsive nature of SPU, but that, as expected for polymeric materials, the general trends of the temperature and the rate dependence mirror each other. However, this behaviour is more complicated than observed for many other polymeric materials, as a result of the richer range of transitions that influence the behaviour over the range of temperatures and strain rates tested.

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A self-repairing, supramolecular polymer system: healability as a consequence of donor–acceptor π–π stacking interactions

Cited by 504 publications

References 31 publications

Optically healable supramolecular polymers

Optically healable supramolecular polymers

Mechanochemistry in Polymers with Supramolecular Mechanophores

Effect of temperature and strain rate on the compressive behaviour of supramolecular polyurethane

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