A Bioinspired Ultratough Multifunctional Mica-Based Nanopaper with 3D Aramid Nanofiber Framework as an Electrical Insulating Material

Abstract

The rapid development of modern electrical equipment toward miniaturization and high power puts forward stringent requirements to the mechanical reliability, dielectric property, and heat resistance of electrical insulating materials. Simultaneous integration of all these properties for mica-based materials remains unresolved. Herein, inspired by the three-dimensional (3D) chitin nanofiber framework within the layered architecture of natural nacre, we report a large-area layered mica-based nanopaper containing a 3D aramid nanofiber framework, which is prepared by a sol−gel−film transformation process. The coupling of 3D aramid nanofiber framework and oriented mica nanoplatelets imparts the nanopaper with good mechanical strength, particularly outstanding ductility (close to 80%) and toughness (up to 109 MJ m −3 ), which are 4−240 and 6−220 times higher than those of all other nacre-mimetics. Meanwhile, the excellent mechanical properties are integrated with high dielectric strength (164 kV mm −1 ), excellent heat resistance (T g = 268 °C), good solvent resistance, and nonflammability, much better than conventional mica-based materials. Additionally, we successfully demonstrate its continuous production in the form of nanotape. The fabulous multiproperty combination and continuous production capability render the mica-based nanopaper a very promising electrical insulating material in miniaturized high-power electrical equipment.

Influence of biological origin on the tensile properties of cellulose nanopapers

“…Fibrillar networks, particularly those built of nanoscale fibers, are the route forward for the development of new membranes and composites, as well as a host of high-end applications, including sensors, optically responsive templates, and flexible electronics. (Sun et al 2018;Wang et al 2019a;Yang et al 2020a;Zeng et al 2020) Recently, as a result of advanced fibrillation techniques, cellulose nanofibers (CNFs) have emerged as an alternative material for network preparation into so-called cellulose nanopapers. (Barhoum et al 2017;Dai et al 2018;Fang et al 2014;Henriksson et al 2008;Toivonen et al 2018;Yang et al 2020b;Zhu et al 2015) CNFs are attractive since they are renewable, lightweight yet very strong, and can be extracted from sustainable raw materials.…”

Fabrication, Applications, and Prospects of Aramid Nanofiber

“…[ 67 ] Earlier studies have demonstrated that ANF prepared by deprotonation is negatively charged, which guarantees its good dispersibility in a system and generates a homogenous and transparent ANFs/DMSO dispersion. [ 68 ] Therefore, many film‐forming technologies such as spin‐coating, [ 62 ] the LBL deposition method, [ 4 ] and electrophoretic deposition [ 69 ] could be utilized to prepare ANF film. Previously, a thin and uniformly distributed ANF/DMSO sol was first formed, and then it was immersed in a water bath to finish the protonation process to obtain an ANF film.…”

“…Reproduced with permission. [ 62 ] Copyright 2020, American Chemical Society. C) VAF film procedure.…”

“…As illustrated in Figure 11B, a continuous sol–gel film transformation setup was designed: it comprised an injection system, a die, a conveyor belt, a water tank, and a hot air drying section. [ 61,62 ] First, an ANF/DMSO solution was dispensed onto a Teflon coated conveyor belt to form a smooth layer of ANF/DMSO sol by a syringe pump at a speed of 0.6 mL min −1 . The conveyor belt was then passed through a water bath at a speed of 15 cm min −1 to accomplish the solvent exchange process, in which the KOH and DMSO were washed out and an ANF gel was formed.…”

Bioinspired Dielectric Film with Superior Mechanical Properties and Ultrahigh Electric Breakdown Strength Made from Aramid Nanofibers and Alumina Nanoplates

“…Wang et al claimed that composite films with exceptional insulating properties could be prepared by constructing three-dimensional “brick-and-mortar” layered structures using ANFs and mica nanoplates. As a result, a high dielectric breakdown strength of 164 kV/mm was achieved for the composite film [ 15 ]. In addition, the precise design of the inorganic–organic interface is another important factor to fulfill the composite’s properties.…”