Chemistry of Crosslinking Processes for Self‐Healing Polymers

Billiet, Stijn; Hillewaere, Xander; Teixeira, Roberto F. A.; Prez, Filip Du

doi:10.1002/marc.201200689

Cited by 279 publications

(204 citation statements)

References 186 publications

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“…The former operates through reversible inter-and/or intra-macromolecular interaction (like hydrogen bond [5], π-π stacking [6], ionic interaction [7], host-guest interaction [8], metal-ligand coordination [9], imine bond [10,11], Diels-Alder bond [12], disulfide bond [13], C-ON bond [14], coumarin derivatives [15], and boronic ester linkages [16]), while the latter relies on the embedded healing agent (mostly fluidic) stored in microcapsules [17,18] or microtubes [19,20]. Compared to intrinsic selfhealing, extrinsic self-healing is able to burst out fluidic healing agent upon cracking so that it is in a better position to realize high speed rehabilitation [21][22][23][24][25][26]. On the basis of this consideration, a few fast healing chemistries and the related healing systems were successively explored in our laboratory [27][28][29][30][31][32][33].…”

Section: Introductionmentioning

confidence: 99%

Improvement of fatigue resistance of epoxy composite with microencapsulated epoxy-SbF5 self-healing system

Ye¹,

Zhu²,

Yuan³

et al. 2017

Express Polym. Lett.

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Abstract. Rapid retardation and arresting of fatigue crack are successfully realized in the epoxy composite containing microencapsulated epoxy and ethanol solution of antimony pentafluoride-ethanol complex (SbF 5 ·HOC 2 H 5 /HOC 2 H 5 ). The effects of (i) microcapsules induced-toughening, (ii) hydrodynamic pressure crack tip shielding offered by the released healing agent, and (iii) polymeric wedge and adhesive bonding of cured healing agent account for extension of fatigue life of the material. The two components of the healing agent can quickly react with each other soon after rupture of the microcapsules, and reconnect the crack only 20 seconds as of the test. The applied stress intensity range not only affects the healing efficiency, but also can be used to evaluate the healing speed. The present work offers a very fast healing system, and sets up a framework for characterizing speed of self-healing.Keywords: smart polymers, fracture and fatigue, self-healing, epoxy eXPRESS Polymer Letters Vol.11, No.11 (2017) [34,35]. In other words, retardation or arresting of fatigue crack is rather sensitive to the polymerization rate of healing agent. Therefore, the effect of fatigue crack induced liberation of healing agent can be conveniently monitored by mechanical response of the composite, i.e. in-situ crack re-binding and growth under cyclic stress. In contrast, other destructive characterization methods, like tensile [15] and impact tests [24,27], need time for manually recombining the fractured specimens for healing and quite a few fast healing agent would have been cured in advance. The measured dependence of healing efficiency on healing time has to be associated with large error. So far, fatigue resistance of self-healing polymers and polymer composites has not been extensively studied. Moreover, healing speed is not the main concern of these available works [35][36][37][38][39][40][41][42][43]. In this context, the present investigation might add to the researches in this area. Experimental 2.1. MaterialsDiglycidyl ether of bisphenol A (EPON 828, epoxy value: 0.53~0.54 mol/100 g), supplied by Shell Co., served as the composite's matrix and the polymerizable component of healing system. Antimony pentafluoride (SbF 5 ) was purchased from Tianjin Institute of Physical and Chemical Engineering of Nuclear Industry, China. Borontrifluoride-2,4-dimethylaniline-complex (BF 3 ·DMA) and methyl hexahydrophthalic anhydride (MHHPA) were bought from Energy Chemical, Shanghai, China. Ethanol, tetraethyl orthosilicate (TEOS), styrene and methyl acrylate were supplied by Alfa Aesar GmbH, Germany. Prior to use, styrene and methyl acrylate were washed with sodium hydroxide aqueous solution (5 wt%), thereafter three times with water, dried over magnesium sulphate, and evaporated to dryness in vacuum. Azobisisobutyronitrile (AIBN) was obtained from Sigma-Aldrich, and purified by recrystallization.Melamine and formaldehyde were supplied by Sinopharm Chemical Reagent Co., Ltd, Shanghai, China. Specimens preparationEpoxy mono...

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Section: Introductionmentioning

confidence: 99%

Improvement of fatigue resistance of epoxy composite with microencapsulated epoxy-SbF5 self-healing system

Ye¹,

Zhu²,

Yuan³

et al. 2017

Express Polym. Lett.

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“…Selection of shell wall with good mechanical properties is also important, because of particle dispersion in polymer matrix without significant loss of healing agent [4]. Wider spectrum of healing chemistries forced development of different microcapsule shell walls and methods of their synthesis [5][6][7]. Most common materials used for shell wall are polyureas [8][9][10], polyurethanes [3,11,12], melamine-formaldehyde [13][14][15] and ureaformaldehyde [2,16,17].…”

Section: Introductionmentioning

confidence: 99%

Polythiourethane microcapsules as novel self-healing systems for epoxy coatings

2017

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A novel group of microcapsule-based self-healing systems for epoxy coatings was developed. Microcapsules with polythiourethane shell wall were synthesized via interfacial polymerization from selected diisocyanates and thiols and dispersed in epoxy matrix. The obtained composites were tested for their selfhealing efficiency using three-point bending test (TPBT) and scratch test. Two sets of each composite samples as well as reference (neat diglycidyl ether of bisphenol A epoxy with polyamine adduct hardener) were tested with TPBT using two methods. Standard method according to ISO 178 was applied for the first set and custom method with pre-bending with 20 N force and standard TPBT after 24 h of selfhealing-for the second set. Pre-bending was applied to obtain microcracks (without sample cracking) for internal self-healing process occurrence. Scratch test allowed to evaluate self-healing efficiency at composite surface and chemical resistance of samples. FT-IR spectroscopy was conducted to confirm occurrence of self-healing process based on polyurethane secondary network forming.

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“…Selfhealing mechanism in bulk polymer materials are either based on release of repair agents upon damage (Lee et al 2011) or on the inclusion of latent molecular functionalities in the polymer structure that trigger repair via thermally reversible reactions, hydrogen bonding, ionomeric arrangements, or molecular diffusion and entanglement (Bergman & Wudl. 2008;Billiet et al 2013). Of them, self-healing hydrogel has attracted much attention due to their great potential in biomedical applications (Deng et al 2012;Phadke et al 2012).…”

Section: Introductionmentioning

confidence: 99%