Large‐Scale Production of Rectorite Nanosheets and Their Co‐Assembly with Aramid Nanofibers for High‐Performance Electrical Insulating Nanopapers

Compared with raw rectorite microplatelets (RMs), rectorite nanosheets (RNs) have considerably greater application prospects in the preparation of advanced composite materials because of their larger aspect ratio, higher surface reactivity, and intrinsically superior mechanical and physical properties. However, the difficulty in the efficient preparation of RNs significantly limits their large-scale applications. Here, a scalable poly(vinylpyrrolidone)-assisted stirring approach is developed to prepare ultrathin RNs from the abundant natural RMs. A higher production rate (≈0.675 g h-1 ) is achieved compared with that of most other nanosheets. Additionally, instead of using conventional time- and energy-consuming high-speed centrifugation, an efficient poly(dienedimethylammonium chloride)-assisted sedimentation strategy is proposed here to rapidly separate the exfoliated RNs from the RN dispersion. Then, the RNs are co-assembled with aramid nanofibers (ANFs) into large-scale nacre-mimetic ANF-RN nanopapers with considerably enhanced mechanical, electrical insulating, and high-temperature-resistant properties compared with pure ANF nanopapers and ANF-RM micropapers. Moreover, these properties are superior to those of previously reported ANF-based nanopapers and commercial insulating micropapers.