Self-healable, strengthened, shape memory elastomers enabled by dual cross-linked networks

We propose a strategy of combining covalent and noncovalent cross-links into carboxyl nitrile rubber (XNBR) networks to fabricate multifunctional elastomers with self-healing and shape memory ability. Specially, commercially available XNBR was cross-linked by diethylenetriamine (DETA) and trimethylolpropane tris(3-mercaptopropionate) (TMPT) through hydrogen bond interaction and thiol-ene “click” reaction, generating reversible hydrogen bonds and robust covalent bonds cross-links, respectively. The modulus of the resulted polymers is consistently enhanced with the increase of TMPT loading, indicating the cross-linking networks are gradually constrained. In addition, the samples demonstrate self-healing and shape memory functions due to the reversible hydrogen bonds and robust covalent cross-links. When the content of TMPT is 0, the sample shows the high elongation at break and appropriate tensile strength. It can achieve almost complete healing due to the material contains noncovalent bonds only. When the content of TMPT is 2 phr, the sample exhibits both pretty self-healing and moderate shape memory ability. This strategy might provide an alternative way to construct intelligent multifunctional polymers with versatile functions.