A theory of healing at a polymer-polymer interface

Kim, Young Hwa; Wool, Richard P.

doi:10.1021/ma00241a013

Cited by 533 publications

(334 citation statements)

References 7 publications

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“…However, the physical properties of the virgin polymer matrix affected the healing ability of the proposed systems. Thus, samples containing low amounts of aromatic disulfide did not present enough polymer chain mobility to permit the material diffusion in the fractured surface, and as a result, they did not present healing characteristics [10,44]. In contrast, low amounts of alkoxysilane precursors led to materials with low crosslinking degrees and, therefore, with poor structural integrity.…”

Section: Evaluation Of the Healing Propertiesmentioning

confidence: 98%

Autonomic healable waterborne organic-inorganic polyurethane hybrids based on aromatic disulfide moieties

Aguirresarobe¹,

Martin²,

Fernández‐Berridi³

et al. 2017

Express Polym. Lett.

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Abstract. Aromatic disulfide dynamic structures were incorporated as chain extenders in waterborne organic-inorganic polyurethane hybrids in order to provide autonomic healable characteristics. The synthesis was carried out following the acetone process methodology and the influence of the introduction of the healing agents in the polymer dispersion stability was analyzed. After the crosslinking process at room temperature, organic-inorganic hybrid films, which presented autonomic healing characteristics, were obtained. These features were evaluated by means of stress-strain tests and the films showed repetitive healing abilities. Thus, the optimum healing time at room temperature (25°C) as well as the influence of different parameters in the healing efficiency, such the aromatic disulfide concentration or the physical properties of the polymer matrix were analyzed.

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Section: Evaluation Of the Healing Propertiesmentioning

confidence: 98%

Autonomic healable waterborne organic-inorganic polyurethane hybrids based on aromatic disulfide moieties

Aguirresarobe¹,

Martin²,

Fernández‐Berridi³

et al. 2017

Express Polym. Lett.

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“…[4][5][6][8][9][10][11][12][13][14][15][16][17][18] Experiments 4,8,9 have found a correlation between the mechanical strength and the interfacial width. For homopolymers, the growth of interfacial width with time has been explained using reptation theory.…”

Section: Introductionmentioning

confidence: 97%

“…For homopolymers, the growth of interfacial width with time has been explained using reptation theory. [10][11][12][13][14][15][16] For immiscible polymers, the free energy cost of mixing limits interdiffusion, causing both the interfacial width and strength to saturate. 17,19,20 Theories have interpreted the growth of strength with time in terms of entanglements, [10][11][12][13][14][15][16][17] but experiments can not directly image entanglements to test these predictions.…”

Section: Introductionmentioning

confidence: 99%

Tensile Fracture of Welded Polymer Interfaces: Miscibility, Entanglements, and Crazing

Grest

Robbins

2014

Macromolecules

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Large-scale molecular simulations are performed to investigate tensile failure of polymer interfaces as a function of welding time t. Changes in the tensile stress, mode of failure and interfacial fracture energy G I are correlated to changes in the interfacial entanglements as determined from Primitive Path Analysis. Bulk polymers fail through craze formation, followed by craze breakdown through chain scission. At small t welded interfaces are not strong enough to support craze formation and fail at small strains through chain pullout at the interface. Once chains have formed an average of about one entanglement across the interface, a stable craze is formed throughout the sample. The failure stress of the craze rises with welding time and the mode of craze breakdown changes from chain pullout to chain scission as the interface approaches bulk strength. The interfacial fracture energy G I is calculated by coupling the simulation results to a continuum fracture mechanics model. As in experiment, G I increases as * To whom correspondence should be addressed † Johns Hopkins University ‡ University of North Carolina ¶ Sandia National Laboratories 1 arXiv:1410.1917v1 [cond-mat.soft] 7 Oct 2014 t 1/2 before saturating at the average bulk fracture energy G b . As in previous simulations of shear strength, saturation coincides with the recovery of the bulk entanglement density. Before saturation, G I is proportional to the areal density of interfacial entanglements. Immiscibiltiy limits interdiffusion and thus suppresses entanglements at the interface. Even small degrees of immisciblity reduce interfacial entanglements enough that failure occurs by chain pullout and

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“…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.…”

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confidence: 99%

Optically healable supramolecular polymers

Burnworth

Tang

Kumpfer

et al. 2011

Nature

1,633

1,327

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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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A theory of healing at a polymer-polymer interface

Cited by 533 publications

References 7 publications

Autonomic healable waterborne organic-inorganic polyurethane hybrids based on aromatic disulfide moieties

Autonomic healable waterborne organic-inorganic polyurethane hybrids based on aromatic disulfide moieties

Tensile Fracture of Welded Polymer Interfaces: Miscibility, Entanglements, and Crazing

Optically healable supramolecular polymers

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