Dual Sulfide–Disulfide Crosslinked Networks with Rapid and Room Temperature Self‐Healability

Abstract

Polymer-based crosslinked networks with intrinsic self-repairing ability have emerged due to their built-in ability to repair physical damages. Here, novel dual sulfide-disulfide crosslinked networks (s-ssPxNs) are reported exhibiting rapid and room temperature self-healability within seconds to minutes, with no extra healing agents and no change under any environmental conditions. The method to synthesize these self-healable networks utilizes a combination of well-known crosslinking chemistry: photoinduced thiol-ene click-type radical addition, generating lightly sulfide-crosslinked polysulfide-based networks with excess thiols, and their oxidation, creating dynamic disulfide crosslinkages to yield the dual s-ssPxNs. The resulting s-ssPxN networks show rapid self-healing within 30 s to 30 min at room temperature, as well as self-healing elasticity with reversible viscoelastic properties. These results, combined with tunable self-healing kinetics, demonstrate the versatility of the method as a new means to synthesize smart multifunctional polymeric materials.

Oxidation‐Responsive Materials: Biological Rationale, State of the Art, Multiple Responsiveness, and Open Issues

“…Compatibility with Thiol Click Chemistries : “Click” reactions are typically quantitative processes occurring under mild conditions and with a reactivity often orthogonal to those of most other functional groups; these versatile processes are extensively used in polysulfide synthesis. For example, thiol‐ene reactions are used in the preparation of (protected) initiators for episulfide polymerization, as the propagation (and cross‐linking) steps (see also the recent review by Araujo), as end‐capping reactions, for post‐polymerization curing, or as side‐chain modifiers . Michael‐type addition has also been widely used as a propagation reaction (for poly(ester sulfide)s), for end‐capping/chain extension, and cross‐linking purposes …”

Trapping Dynamic Disulfide Bonds in the Hard Segments of Thermoplastic Polyurethane Elastomers

“…There are a growing number of dynamic covalent bonds and reactions that have been incorporated into polymers, including alkoxyamine bonds, Diels–Alder adducts, olefin metathesis, and transesterification reaction, to name a few . The disulfide bond has been a popular choice to incorporate into polymer architectures as a consequence of the commercially availability of a wide range of thiol/disulfide compounds and the disulfide's responsiveness toward various external stimuli, such as light, pH, ultrasound, or heat . A variety of polymeric materials where the thermally triggered disulfide exchange has been employed have been reported, most of which utilized either a catalyst or the equilibrium between thiolate anion and disulfide .…”

Self-Healing Polymer Composites for Structural Application

“…It is accomplished by reversible chemical reactions upon an external stimulus. Typical dynamic bond chemistry is belonging to disulfide [56], hindered urea [57], and alkoxyamine [58] that are having flexible bonding units. A polymer (3M4F) system demonstrated self-repairing by subjecting it to heating/cooling cycles [18] shown in Figure 7.…”