Constrained noncovalent interfaces enable strain hardening in nacre-like rGO/melamine films

Layered graphene oxide (GO) films are promising structural materials, but their strength and ductility are limited by weak, porous interfaces that lose load transfer during interlayer sliding. Here we report a nacre-like reduced graphene oxide/melamine (rGO/Mel) film coupling dense lamellar stacking with strong, constrained yet dynamically reconfigurable noncovalent interactions. Melamine is introduced between GO sheets and retained after hydroiodic acid reduction, while the reduced sheets form flatter, more compact stacks with smaller interlayer spacing. Melamine’s triazine rings interact with graphitic domains through π–π stacking, and its amine groups form reversible hydrogen bonds with residual oxygen-containing groups, sustaining shear transfer while allowing controlled sliding. Under tensile loading, rGO/Mel exhibits pronounced post-yield strain hardening associated with nanosheet straightening, interfacial reorientation and continued molecular bridging. The optimized film reaches a tensile strength of 262.7 MPa, a strain at break of 5.0 % and a toughness of 6.0 MJ m⁻ 3 . These values represent increases of 538 %, 317 % and 2900 % over pure GO, respectively. Molecular dynamics simulations support this picture by showing more stable interlayer contact and melamine-assisted shear transfer in rGO/Mel. This work shows that constrained noncovalent interfaces can turn interlayer sliding from a failure pathway into a source of strain hardening in layered nanocomposites.