Bioinspired self-assembled films of carboxymethyl cellulose–dopamine/montmorillonite

Among cellulose-based materials, carboxymethyl cellulose (CMC) can be used as an alternative eco-friendly packaging material. However, the conservation of high stiffness and strength against hydration-induced decay of mechanical properties at a high humidity remains a fundamental challenge in such water-borne materials. Inspired by mussel adhesive proteins (adhesive) and nacre (brick-and-mortar structure), in this work, a bio-inspired multifunctional CMC composite was conjugated to dopamine (DA) and subsequently assembled with montmorillonite (MTM) to generate bio-inspired and layered nanocomposite films using a simple vacuum filtration-assisted assembly method. The modified CMC and composite films were comprehensively characterized, particularly with XPS and NMR. The conjugation of DA on CMC resulted in nanocomposites with an improved stability in the wet state and increased tensile strength (162.0 MPa) and elastic modulus (8.7 GPa) at a relative humidity of up to 90%. Thermogravimetric analysis and a horizontal flame test also showed that the nanocomposites possessed a high thermal stability and were able to self-extinguish immediately after removal of the flame. Therefore, the facile strategy developed in this work provides a promising approach to prepare biomimetic materials with excellent moisture resistance and flame retardancy, which have great potential for various applications.