Multifunctional nacre-mimetic Ti₃C₂T_x films with tunable conductivity and mechanical properties by controlling interlay supramolecular interactions

Nacre-mimetic strategy provides an enlightening approach to design high-performance bioinspired nanocomposites. Yet, it is still a big challenge to integrate excellent mechanical properties and tunable multifunctionality into artificial nacre materials. Herein, we develop a pioneering strategy to simultaneously modulate the electrical conductivity and mechanical properties of nacre-mimetic nanocomposite films by controlling interlay supramolecular interactions. A series of novel waterborne polyurethanes with 2-ureido-4[1H]-pyrimidinone (UPy) quadruple hydrogen bonding motifs in the side-chains were elaborately designed and synthesized, and further assembled with Ti₃C₂T_x MXene nanosheets to construct lamellar nacre-mimetic nanocomposite films with highly ordered nanostructure. This research revealed for the first time that merely varying the content of UPy groups on polyurethane realize significant modulation of mechanical properties, electrical conductivity, and even the electromagnetic shielding effectiveness of nacre-mimetic nanocomposites. Strikingly, the tensile strength of the nanocomposites can be improved from 87.91 to 136.96 MPa and the electrical conductivity from 3214.0 to 4136.1 S cm⁻¹ when the UPy content is increased from 0 to 15%. Additionally, the nacre-mimetic nanocomposite film is capable of fast responsive Joule heating performance at low trigger voltage. This work would open up a new avenue for fabricating multifunctional and mechanically robust biomimetic nanocomposites.