Dynamically Cross-linked Elastomer Hybrids with Light-Induced Rapid and Efficient Self-Healing Ability and Reprogrammable Shape Memory Behavior

Abstract

Pristine carbon nanotubes (CNTs) were activated to exhibit Diels-Alder (DA) reactivity in a polymer matrix, which was modified with monomers containing furan groups. The DA-active polymer matrix was transferred into a dynamic reversible cross-linked inorganic-organic network via a Diels-Alder reaction with CNTs, where pristine CNTs were used as dienophile chemicals and furan-modified SBS acted as the macromolecular diene. In this system, the mechanical properties as well as resilience and solvent resistance were greatly improved even with the presence of only 1 wt % CNTs. Meanwhile, the hybrids retained recyclability and exhibited some smart behaviors, including self-healing and reprogrammable shape memory properties. Furthermore, due to the photothermal effect of CNTs, a retro-Diels-Alder (rDA) reaction was activated under laser irradiation, and healing of a crack on the hybrid surface was demonstrated in approximately 10 s with almost complete recovery of the mechanical properties. Such fast and efficient self-healing performance provides a new concept in designing self-healing nanocomposites with tunable structures and mechanical properties. Furthermore, the DA and rDA reactions could be combined to reprogram the shape memory behavior under laser irradiation or thermal treatment, wherein the temporary shape of the sample could be transferred to a permanent shape via the rDA reaction at high temperature.

Flourishing Self‐Healing Surface Materials: Recent Progresses and Challenges

“…Recently, it was reported that the addition of carbon nanotubes, graphene oxide nanosheets, and other nanoparticles into polymer matrix surface activated the reactivity of DA due to their outstanding photothermal effect. [114][115][116] For instance, the carbon nanotubes (CNTs) were embedded into the polymer matrix surface modified by monomers containing furan groups (Figure 11b,c). [116] Under the laser irradiation, the surface cracks can be efficiently healed since the photothermal effect of CNTs activated the DA reaction at interface (Figure 11d).…”

“…[114][115][116] For instance, the carbon nanotubes (CNTs) were embedded into the polymer matrix surface modified by monomers containing furan groups (Figure 11b,c). [116] Under the laser irradiation, the surface cracks can be efficiently healed since the photothermal effect of CNTs activated the DA reaction at interface (Figure 11d). After that, different concentrations of graphene oxide nanosheets enhanced the healing effect of polyurethane as illustrated in the Figure 11e, [115] generated heat under light and further promoted DA reaction at interface as demonstrated in Figure 11f.…”

“…d) Picture of sample with CNTs before irradiation and picture of sample after healing for 10 s. b-d) Reproduced with permission. [116] Copyright 2017, American Chemical Society. e) The healing efficiency of different samples.…”

Thermoreversible Polymeric Nanocomposites

“…Properties such as self-healing and shape memory, besides the "classical effects" on thermal and mechanical ones, are easily added to the composite behavior. The sensitivity to multiple external stimuli such as electricity, irradiation, and heat [11,18,53,54], represents a focal point for the design of smart materials. An added value in this case is the possibility (via irradiation) of remote-induced self-healing as well as of ultrafast kinetics [55].…”

“…One of the main driving forces behind the use of such a strategy is the presence of special end properties. For example, the dynamic nature of thermally reversible interactions (as a function of temperature) endows composites with self-healing behavior [11,13,[15][16][17] and shape-memory characteristics [18,19].…”