Triple-Action Self-Healing Protective Coatings Based on Shape Memory Polymers Containing Dual-Function Microspheres

Abstract

In this study, a new self-healing shape memory polymer (SMP) coating was prepared to protect the aluminum alloy 2024-T3 from corrosion by the incorporation of dual-function microspheres containing polycaprolactone and the corrosion inhibitor 8-hydroxyquinoline (8HQ). The self-healing properties of the coatings were investigated via scanning electron microscopy, electrochemical impedance spectroscopy, and scanning electrochemical microscopy following the application of different healing conditions. The results demonstrated that the coating possessed a triple-action self-healing ability enabled by the cooperation of the 8HQ inhibitor, the SMP coating matrix, and the melted microspheres. The coating released 8HQ in a pH-dependent fashion and immediately suppressed corrosion within the coating scratch. After heat treatment, the scratched coating exhibited excellent recovery of its anticorrosion performance, which was attributed to the simultaneous initiation of scratch closure by the shape memory effect of the coating matrix, sealing of the scratch by the melted microspheres, and the synergistic effect of corrosion inhibition by 8HQ.

A Self-Strengthening Epidermis-Like Smart Coating Enabled by Dynamic Iron Sequestration

“…E and H of the strengthened ELSC in 3.5 wt% NaCl solutions are superior to many materials typically used as the surface protection for steel such as epoxy, polyurethane, polystyrene and many others (Figure 3f). [44][45][46][47][48][49][50][51] They are also much higher than the cuticle of mussel thread with an E of 2 GPa and H of 0.1 GPa and a multilayered poly(diallyldimethylammonium chloride)/polyacrylic acid coating (E of 6 GPa and H of 0.22 GPa). This is remarkable considering the hydrophilic nature of ELSM and such result should benefit from the presence of MTM nanosheets in the top layer to ensure the effective load transfer and the minimization of plasticizing effect of water.…”

“…The small fluctuation in impedance values around the scratch area may be a result of structure reorganization. Current self-healing anticorrosion coatings work mainly by directly adding corrosion inhibitors 70,71 or embedding nanocontainers [72][73][74] /capsules 44,47,75 loaded with inhibitors. Once the coating is damaged, the corrosion inhibitors can be released to the damaged area to form a passivation film and prevent further spread of corrosion.…”

Thermo-Responsive Self-Healing Polycaprolactone Urethane Coatings from Waste Palm Cooking Oil

“…This might be due to the longer PCL network in the polymer coating, as the PCL contributes to the soft segments. Huang et al [5] claim that heating above the T m of PCL induced the shape memory effect by mitigating the PCL segments. Consequently, the mechanical scratches or damages could be physically closed conceivably reinstate the barrier properties of the coating [16].…”

“…Other possibilities that have been investigated by the researchers include self-healing materials that facilitate remotely-controlled self-healing after damage to fully restore the mechanical properties of the pristine material and to repair the micron-size cracks or cuts with minimum external intervention [3,4]. There are two popular strategies to synthesize self-healing materials: (i) the impregnation of catalysts such as in fibers or capsules [5,6]; and (ii) through the consolidation of dynamic reversible bonds in the polymer matrix, for example crosslink, oligomers, monomers, and so on.…”

Mesoporous Silica Nanoparticles to Tune Oxidative Degradation Rates in Composite Shape Memory Polymers

“…The products produced over the life of the SMP have been indicated to be cytocompatible at the levels released during mass loss, and more importantly, work by Oliva et al suggests that similar aldehyde functional groups could improve biomaterial-tissue adhesion, and thus this degradation may be fortuitous over the long-term, despite it being reliant upon the cellular response to the material [5,7,8]. In general however, controlling the degradation of SMPs, either by increasing the degradation rate or increasing biostability, would broaden potential medical applications [9][10][11].…”