Nanocellulose-Assisted Exfoliation to Prepare Rectorite-Based Composite Films with Excellent Mechanical, Heat-Resistant, and Flame-Retardant Properties

Rectorite nanosheets (RNs) with large aspect ratios, high surface reactivity, and superior mechanical properties have promising applications in many fields. However, the efficient fabrication and assembly of RNs into high-performance nanocomposites for practical applications remains a challenge. In this work, a facile cellulose nanofiber (CNF)-assisted method was developed for exfoliating high-quality RNs and preparing CNF/RNs nanocomposite films. This method achieved a high yield of 69.1% for RNs with a large aspect ratio of ∼144. The CNF/RNs nanocomposite films formed via vacuum filtration showed a highly ordered “brick-and-mortar” microstructure with outstanding mechanical properties. Especially, the optimized CNF/RNs nanocomposite film with 20 wt % RNs (CR-20) had a tensile strength of ∼219 MPa and a Young’s modulus of ∼1.7 GPa, along with excellent heat-resistant performance. Moreover, the CR-20 film displayed a high limiting oxygen index (LOI) of 32.1% and self-extinguishing behavior in vertical combustion experiments. Our proposed strategy provides an avenue for fabricating high-performance rectorite-based nanocomposites, which have great potential as substrates for solid-state electrolytes, wearable sensors, and aerospace applications.