UV-initiated self-healing of oxolane–chitosan–polyurethane (OXO–CHI–PUR) networks

Ghosh, Biswajit; Chellappan, Kishore V.; Urban, Marek W.

doi:10.1039/c2jm31126g

Cited by 46 publications

(27 citation statements)

References 13 publications

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“…Experimentally, lowering T g and moduli at the cut surfaces in self‐healable polyurethanes, which are able to recover after healing was observed. [2b,m,9a,91] Also, chain mobility increase inside the cut was also detected via laser speckle imaging (LSI) …”

Section: Discussionmentioning

confidence: 99%

Self‐Healing of Polymers via Supramolecular Chemistry

Yang

Urban

2018

Adv Materials Inter

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156

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rearrangements. While one challenge is to incorporate chemical modifications enabling chemical bond reformations, equally important is the coordination of chemical events with polymer network physical changes within interfacial regions resulting from mechanical damage.Recent studies suggested that two types of dynamic bonds are highly attractive to achieve self-healing in polymers: reversible covalent bonds and supramolecular chemistry. Reversible covalent bonds offer higher bonding energies, allowing the material to regain physical properties similar to conventional polymers prior to damage. Advantages and disadvantages of reversible covalent bonding were summarized in several review articles. [5] Self-healing involving dynamic dissociation/association using supramolecular chemistry offers fast reversibility under ambient conditions reaching exceptionally quickly equilibrium state, bonding directionality, and remarkable sensitivity. Since broad-range of network structures can be obtained via supramolecular interactions, applications in soft electronics, sensing, biomedical technologies, 3-4D printing, and reprocessable materials are highly attractive and may open many new technological opportunities (Figure 1). Mechanical integrity using supramolecular chemistry is achieved by the formation of multiple noncovalent interactions between multiple associative groups covalently attached to polymer side chain or chain ends of macromolecular building blocks. These interactions include H-bonding, metal-ligand complexation, hostguest, ionic interactions, π-π stacking, and hydrophobic interactions. They are depicted in Figure 1. In contrast to covalent rebonding, mechanical properties of supramolecular polymer networks are achieved by the presence of these secondary interactions forming noncovalent crosslinks, which bind liquid-like building blocks into plastic or rubbery polymers in hydrated and nonhydrated states. The dynamic nature of these noncovalent bonds provides an opportunity for self-healing attributed to reassociation of supramolecular components, similar to secondary interactions found in living systems that regulate many living functions. The rule of thumb in designing these networks is that the degree of association is determined by the equilibrium constant (K a ) values, whereas dynamics is driven by rate constants of the association-dissociation reactions, k a and k d , respectively. [6] Molecular structural and electronic features along with network heterogeneities are of particular importance in these networks. Mechanical strength and elasticity of supramolecular polymers are determined by not only the K a values, but also stacking and clustering of the associative groups which may result in heterogeneities leading to the Recent advances of supramolecular chemistry utilized in the development of self-healing polymers have revealed that the rate and equilibrium constants of bond dissociation/re-association, bonding directionality, chain relaxation time, decay rate of chain relaxation after damage, and clu...

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Section: Discussionmentioning

confidence: 99%

Self‐Healing of Polymers via Supramolecular Chemistry

Yang

Urban

2018

Adv Materials Inter

Self Cite

156

117

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“…Later, Burnworth et al presented rubbery metallosupramolecular polymers with non-covalent metal-ligand motifs converting a UV light energy into heat to quickly and efficiently dissociate and heal the defects [15]. Ghosh et al observed lowering of Tg inside the scratch of damaged polymers, explained by a damage-induced chain scission and recombination reactions [16] and supported using molecular dynamics simulations [17].…”

Section: Introductionmentioning

confidence: 98%

The influence of diol chain extender on morphology and properties of thermally-triggered UV-stable self-healing polyurethane coatings

Grzelak

Boinard

Liggat

2018

Progress in Organic Coatings

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Two sets of waterborne polyurethane dispersions were synthesised from polycarbonate polyol with molecular mass of 500 Da and hexamethylene diisocyanate or isophorone diisocyanate. Formulations were prepared without a chain extender, with aliphatic diol with two to five carbon atoms or with diethylene glycol. Coatings were prepared on cellulose triacetate sheets, damaged by a steel-wool scratch instrument and left to heal at room temperature and at 60˚C. Self-healing efficiency was examined by comparison of haze before damage and at intervals after damage. Samples were analysed using Differential Scanning Calorimetry, Attenuated Total Reflectance Fourier Transform Infrared Spectroscopy, Scanning Electron Microscopy. The tests were repeated after 12 weeks to investigate ageing of the polymers. Samples were also tested for their stability to weathering. Optimally designed coatings obtained up to 100% recovery within 10 minutes at 60˚C and partial recovery at room temperature. The self-healing properties of coatings were found to be linked to macro-organisation of polymer chains caused by interactions between hard segments and soft segments of the polyurethane moiety, leading to phase-mixing, promoted by bulky, non-symmetrical isophorone diisocyanate, or phase-separation, promoted by linear, symmetrical hexamethylene diisocyanate. The length of chain extender was found to have large influence on formulations prepared with hexamethylene diisocyanate, increasing phase-separation and haze with the increase of chain length. Diethylene glycol was found to improve phase-mixing and self-healing properties of hexamethylene diisocyanate based materials. The influence of chain extenders was found to be minimal for isophorone diisocyanate based materials.

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“…A UV‐activated healing mechanism has been reported for PUs and PDMSs . These systems contain dynamic reversible bonds activated by UV exposure to repair damage.…”

Section: Introductionmentioning

confidence: 99%

“…[19] A UV-activated healing mechanism has been reported for PUs and PDMSs. [21][22][23] These systems contain dynamic reversible bonds activated by UV exposure to repair damage. UV-responsive polymers have also been used to form microcapsule shell walls.…”

Section: Introductionmentioning

confidence: 99%

Sunlight‐Activated Self‐Healing Polymer Coatings

Odarczenko

Thakare

et al. 2019

Adv Eng Mater

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UV light can cause damage to polymer coatings used in transportation, oil, and agricultural industries, requiring costly repair or replacement of the coating. Herein, a self‐healing epoxy coating is developed so that UV light activates a desirable autonomous healing response to mechanical damage. The coatings contain a single type of microcapsule with a UV‐curable epoxy healing chemistry in the core and a novel UV‐protecting shell wall with embedded carbon black particles. Photo‐differential scanning calorimetry reveals that up to a 65% degree of protection is provided by the UV‐blocking shell wall after UV exposure. The addition of a polyurethane (PU) top coat provides further increase in the level of protection (≈100%). After damage with a scribe and exposure to UV, the presence of healed epoxy is confirmed by confocal Raman and fluorescent spectroscopy. The anticorrosion performance of healed coatings on steel substrates is assessed after exposure to a simulated saltwater solution. The UV‐curable, self‐healing coating exhibits significantly less corrosion than a control coating with no self‐healing ability.

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UV-initiated self-healing of oxolane–chitosan–polyurethane (OXO–CHI–PUR) networks

Cited by 46 publications

References 13 publications

Self‐Healing of Polymers via Supramolecular Chemistry

Self‐Healing of Polymers via Supramolecular Chemistry

The influence of diol chain extender on morphology and properties of thermally-triggered UV-stable self-healing polyurethane coatings

Sunlight‐Activated Self‐Healing Polymer Coatings

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