Interlayer Inorganic Ionic Polymerization of 2D Nanosheets for Ultratough Structural Materials

ABSTRACT Integrating both high strength and high toughness into 2D nanocomposites remains a significant challenge owing to the limited interfacial interactions between nanosheets. Here, an interlayer inorganic ionic polymerization (IIIP) strategy is proposed to effectively achieve a combination of high strength and ultrahigh toughness. Specifically, calcium phosphate oligomers (CPO) are anchored onto montmorillonite (MMT) to obtain CPO/MMT composite nanosheets. Polyvinyl alcohol (PVA) and sodium alginate (SA) are incorporated into CPO/MMT interlayers to regulate ionic polymerization of CPO, thereby creating an organic–inorganic dual bridge between MMT nanosheets. The resulting PVA/SA/CPO/MMT (PSCM) film demonstrates a highly integrated structure across the nano‐ to macroscale, facilitated by the dual bridge. Consequently, the PSCM film exhibits a record‐breaking ultrahigh toughness (111.7 ± 9.9 MJ m − 3 ), surpassing all previously reported 2D nanocomposites, along with remarkable tensile strength (292.8 ± 12.7 MPa). The PSCM bulk assembled using films as building units demonstrates an excellent bending energy of 34.43 ± 1.97 MJ m − 3 without fracture, along with remarkable toughness under extreme conditions (e.g., −196°C and 200°C). These high‐performance PSCM demonstrate significant application potential in the field of structural engineering materials. The proposed IIIP strategy paves a new avenue for developing ultrahigh‐toughness 2D nanocomposites.