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

Abstract

Materials with excellent thermal stability, mechanical, and insulating properties are highly desirable for electrical equipment with high voltage and high power. However, simultaneously integrating these performance portfolios into a single material remains a great challenge. Here, we describe a new strategy to prepare composite film by combining one-dimensional (1D) rigid aramid nanofiber (ANF) with 2D alumina (Al2O3) nanoplates using the carboxylated chitosan acting as hydrogen bonding donors as well as soft interlocking agent. A biomimetic nacreous ‘brick-and-mortar’ structure with a 3D hydrogen bonding network is constructed in the obtained ANF/chitosan/Al2O3 composite films, which provides the composite films with exceptional mechanical and dielectric properties. The ANF/chitosan/Al2O3 composite film exhibits an ultrahigh electric breakdown strength of 320.1 kV/mm at 15 wt % Al2O3 loading, which is 50.6% higher than that of the neat ANF film. Meanwhile, a large elongation at break of 17.22% is achieved for the composite film, integrated with high tensile strength (~233 MPa), low dielectric loss (<0.02), and remarkable thermal stability. These findings shed new light on the fabrication of multifunctional insulating materials and broaden their practical applications in the field of advanced electrics and electrical devices.

Aramid Nanofiber and Boron Nitride Nanosheet Composite Films for Mechanical and Dielectric Insulation Application

“…BNNS possessed excellent dielectric insulation properties such as high resistivity, low dielectric constant, and low dielectric loss. , As depicted in Figure a,b, the addition of BNNS is also helpful for the enhancement of the dielectric breakdown strength, which for the pure ANF film is 40.4 kV·mm –1 and that for ANF/BNNS-II is 100.7 kV·mm –1 , an increase of 149%. Figure c and Table S5 summarize the dielectric breakdown strength of this work and other ANF-based films. ,,,,,− It can be seen that the insulation properties of ANF/BNNS films in our study are at a high level. A radar chart presents the stress, toughness, and dielectric breakdown strength of the ANF-based films in this work (Figure d), which helps us to clearly compare the comprehensive properties of each sample.…”

“…Zhu et al 24 verified that carbon nanotubes (CNTs) can largely improve the stress of ANF films. Qing and co-workers 25 claimed that aluminum oxide (Al 2 O 3 ) nanoplatelets are beneficial for forming high-ordered arrangements in the ANF frameworks.…”

Biocompatible and breathable healthcare electronics with sensing performances and photothermal antibacterial effect for motion-detecting

“…And new peaks appear in the FT-IR spectra of PMPP (Fig. 2m), 3350 cm −1 , 3180 cm −1 and 1550 cm −1 , ascribed to the stretching vibration and bending vibration of N-H in secondary amide 54,55 . The significant difference indicates the successful encapsulation of PDA on PMP.…”

Aqueous Dispersion of Aramid Nanofibers Achieved by Using Tannic Acid for Ultrahigh Strength Films

“…Most studies on ANFs have been based on deprotonation methods. Due to their good maintenance of the mechanical and thermal properties of pristine aramid fibers, ANFs have found applications in various emerging fields, such as supercapacitors, − sensors, ,, electric heaters, − insulating materials, ,− and electromagnetic shielding materials. , Nevertheless, to the best of our knowledge, ANFs have only been stabilized in potassium hydroxide (KOH)/dimethyl sulfoxide (DMSO) systems. When the dispersion contains proton donors, the poly­( p -phenylene terephthamide) (PPTA) polyanion will acquire hydrogen protons, resulting in instant reprotonation, which leads to the agglomeration of ANFs.…”