Electrically Conductive Kevlar Fibers and Polymer-Matrix Composites Enabled by Atomic Layer Deposition

Abstract

Multifunctional composites that incorporate nonstructural capabilities such as energy storage, self-healing, and structural health monitoring have the potential to transform load-bearing components in automotive and aerospace vehicles. Imparting electrical conductivity into polymer-matrix composites (PMCs) is an important step in enabling multifunctionality while maintaining mechanical stiffness and strength. In this work, electrically conductive PMCs were fabricated by conformally coating Kevlar 49 woven fabrics with aluminum-doped zinc oxide using atomic layer deposition (ALD). Electrical resistance was measured at the single-fiber, single-tow, and woven fabric levels as a function of coating thickness. The ALD coatings on adjacent fibers merge as their thickness increases, resulting in an interconnected network with improved percolation and lower resistance. After ALD, the fabrics were embedded in an epoxy matrix to manufacture PMCs. The electrical resistance of the composites increased with applied tensile strain, which was attributed to cracking of the conductive coatings. The relative change in resistance as a function of strain varied with coating thickness, which was rationalized by a thin-film fracture mechanics model. This work demonstrates a pathway for scalable and tunable incorporation of electrical conductivity into fiber-reinforced composites without significantly changing their density or load-bearing capabilities.

Scaling-Up Seeded Hydrothermal Nanowire Synthesis on Non-planar Surfaces Using a Flow Reactor

“…This fabrication platform can be used in a range of applications where nanostructures must be integrated onto industrially relevant surface geometries and sizes. For example, in addition to the examples provided in this study, surface nanostructuring has also been demonstrated to impart multifunctionality in fiber-reinforced composites and tunable optoelectronic properties for applications in solar energy. ,, To build upon this work, future efforts can further optimize the detailed flow and temperature profile of the reactor for specific target geometries, which could be further informed by computational modeling. We hope that this work will inspire the transition of other nanomaterial synthesis processes to scaled-up, continuous manufacturing platforms to accelerate their commercialization in a range of applications.…”

Atomic-scale engineering of advanced catalytic and energy materials via atomic layer deposition for eco-friendly vehicles

“…For vehicles, ALD has been performed to prepare precious metal or metal oxide nano coatings to improve the performance of micro-electro-mechanical system, such as capacitive sensor, micro-resonator and highpower radar [25][26][27]. The structure components can be modified by ALD coatings to increase the mechanic strength and corrosion resistance [28][29][30][31]. As a promising energy storage device, supercapacitor also requires surface modification on the electrodes to increase the energy density and cyclic stability.…”