Self-healing materials based on disulfide bond-containing acrylate networks

Abstract

Disulfide containing vitrimers are being widely studied to get renewable, reprocessable and self-healable resins. The most of them are based on thermally cured epoxy resin. Herein, new thermoset systems based on typical acrylate monomers with photo-curing were synthesized with self-healing capabilities by introducing monomers with disulfide bonds. These disulfide groups are able to exchange upon heating, leading to a renewal of the crosslinks across the damaged surfaces. Different ratios of associative reversible exchange covalent bonds have been studied. The samples were evaluated in terms of thermal and mechanical properties. It was found that the glass transition temperature (Tg) is lower than that corresponding to typical acrylate thermosets, but mechanical properties are better. Increases in hardness of 2.4 times and in elastic modulus of 1.7 times with respect to the reference networks were achieved. Finally, the self-healing properties of the disulfide acrylates were demonstrated by monitoring the repair of a scratch upon heating. A new experimental test for quantifying the self-healing efficiency has been optimized, following the recovery of the surface crack by perfilometry. The composition optimization allows us to achieve repair percentages of 95% in shorter times.