Fracture and Self-Healing in a Well-Defined Self-Assembled Polymer Network

Skrzeszewska, Paulina J.; Sprakel, Joris; Wolf, Frits A. de; Fokkink, Remco; Stuart, Martien A. Cohen; Gucht, Jasper van der

doi:10.1021/ma1000173

Cited by 131 publications

(173 citation statements)

References 24 publications

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“…3C) likely through restoration of broken catecholato-Fe 3þ cross-links analogous to what has been observed in other types of reversible polymer networks with weaker noncovalent crosslinks such as ionic and hydrogen bonds (22,23). The effects of polymer size, cross-link density, and Fe∶dopa ratio on the relaxation and self-healing time of catecholato-Fe 3þ cross-linked polymer networks are currently under investigation.…”

Section: Discussionmentioning

confidence: 68%

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

Holten‐Andersen

Harrington

Birkedal

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

1,384

1,326

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Growing evidence supports a critical role of metal-ligand coordination in many attributes of biological materials including adhesion, self-assembly, toughness, and hardness without mineralization [Rubin DJ, Miserez A, Waite JH (2010) Advances in Insect Physiology: Insect Integument and Color, eds Jérôme C, Stephen JS (Academic Press, London), pp . Coordination between Fe and catechol ligands has recently been correlated to the hardness and high extensibility of the cuticle of mussel byssal threads and proposed to endow self-healing properties [Harrington MJ, Masic A, HoltenAndersen N, Waite JH, Fratzl P (2010) Science 328:216-220]. Inspired by the pH jump experienced by proteins during maturation of a mussel byssus secretion, we have developed a simple method to control catechol-Fe 3þ interpolymer cross-linking via pH. The resonance Raman signature of catechol-Fe 3þ cross-linked polymer gels at high pH was similar to that from native mussel thread cuticle and the gels displayed elastic moduli (G′) that approach covalently cross-linked gels as well as self-healing properties.biomaterials | catecholate polymer | metal coordination | reversible cross-links | physical gels M ussel byssal threads are protected against wear by a cuticle, an outer proteinaceous coating, that despite a hardness of ∼0.1 GPa, accommodates large cyclic strains in the turbulent intertidal zone (1, 2). During strain, the cuticle suppresses macroscale failure by limiting crack propagation to the microscale (1, 3). It was recently demonstrated that a small amount of Fe (<1 wt%) plays an important role in this mechanism; bonding with the catechol-like amino acid dihydroxy-phenylalanine (dopa) in the cuticle protein, mfp-1 (4-6). Tris-and bis-catecholFe 3þ complexes possess some of the highest known stability constants of metal-ligand chelates (log K S ≈ 37-40, where K S is the equilibrium constant for the complex formation) (7-10) and single molecule tensile tests have demonstrated that the breaking of a metal-dopa bond requires a force only modestly lower than the force required to rupture a covalent bond under identical loading conditions (∼0.8 nN vs. ∼2 nN, respectively) (11). Harrington et al. proposed a model where the catecholFe 3þ complexes in the cuticle function as sacrificial load-bearing cross-links facilitating extensibility of the material (4). In contrast to covalent bonds, metal-dopa bonds can spontaneously reform after breaking (11) and the model predicts that the damage accumulated in the cuticle could self-heal via reformation of broken catechol-Fe 3þ complexes (4). Here we describe a strategy for introducing bis-and/or tris-catechol-Fe 3þ cross-links into a synthetic polymer network and demonstrate that such a network indeed displays high elastic moduli and self-healing properties. ResultsThe stoichiometry of catechol-Fe 3þ complexes (mono-, bis-, or tris-) is controlled by pH via the deprotonation of the catechol hydroxyls (Fig. 1A). The pH required to establish the bis-and tris-complexes is typically reported to be above pH...

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Section: Discussionmentioning

confidence: 68%

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

Holten‐Andersen

Harrington

Birkedal

et al. 2011

Proc. Natl. Acad. Sci. U.S.A.

1,384

1,326

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“…18 This was interpreted as evidence of a 'fluidization' zone in the vicinity of a microscopic fracture plane that grew in thickness with increasing shear rate, possibly corresponding to localized fracture of the gel into smaller fragments.…”

Section: Theoretical Analysis and Discussionmentioning

confidence: 99%

Extreme Strain Localization and Sliding Friction in Physically Associating Polymer Gels

Erk

Martin

et al. 2012

Langmuir

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Model physically associating gels deformed in shear over a wide range of reduced rates displayed evidence of strain localization. The non-linear stress responses and inhomogeneous velocity profiles observed during shear rheometry coupled with particle tracking velocimetry were associated with the occurrence of rate-dependent, banding and fracture-like responses in the gel. Scaling law analysis from traditional sliding friction studies suggests that at the molecular level, deformation is confined to a shear zone with thickness comparable to the gel's mesh size, the smallest structurally relevant length scale in the gel.

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“…Berret et al 7,9 in the shear-thinning regime of aqueous telechelic polymer solutions and by Skrzeszewska et al 26 for telechelic polypeptides; in these studies, the stress maxima were demonstrated by particle image velocimetry, a flow visualization technique, to be due to the formation of a fracture zone within the sample. 9,26 In our solutions, deformation energies of 3-4…”

Section: Rate-dependent Mechanical Instabilitymentioning

confidence: 99%

Rate-Dependent Stiffening and Strain Localization in Physically Associating Solutions

Erk

Shull

2011

Macromolecules

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Model physically associating solutions of acrylic triblock copolymer molecules in a midblockselective solvent displayed nonlinear strain-stiffening behavior which transitioned to rapid strain softening during shear start-up experiments at reduced rates spanning almost 4 orders of magnitude. Softening was believed to result from the shear-induced formation of highly localized regions of deformation in the macromolecular network. This behavior was accurately captured by a model that incorporated the strain energy and relaxation behavior of individual network strands in the solution. Flow curves predicted from the model were nonmonotonic, consistent with the onset of flow instabilities at high shear rates. The nonlinear stress response reported here, coupled with the wide range of accessible relaxation times of these thermoreversible solutions, makes them ideal model systems for studies of failure-mode transitions in physically associating solutions and gels.

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Fracture and Self-Healing in a Well-Defined Self-Assembled Polymer Network

Cited by 131 publications

References 24 publications

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

pH-induced metal-ligand cross-links inspired by mussel yield self-healing polymer networks with near-covalent elastic moduli

Extreme Strain Localization and Sliding Friction in Physically Associating Polymer Gels

Rate-Dependent Stiffening and Strain Localization in Physically Associating Solutions

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