Magnetic Field-Induced Aligned Graphene/Cellulose Conductive Composites for Electroluminescent Devices

Abstract

Graphene is a promising reinforcement for fiber composite materials in flexible wearable applications because of its exceptional conductivity. Researchers have focused on bridging the gap between the intrinsic conductivity of graphene and the macroscopic performance of composite materials. The anisotropy of 2D nanomaterials indicates that their orientation and distribution are crucial factors in determining the macroscopic performance of thin films and bulk materials. Various technologies developed to control the formation of microstructures include electric and magnetic field methods, hot pressing, centrifugation, and freeze-drying. In this study, we prepared flexible graphene/cellulose composite film materials and used magnetic fields to regulate the orientation and distribution of graphene within cellulose paper. Results show that the grid structure of graphene arranged on the composite material produced interconnected conductive paths and reduced the graphene permeation threshold. By giving the conductive layer a higher dielectric constant, we prevented its breakdown as a conductive film. Electroluminescent devices were constructed using graphene/cellulose flexible composite materials and achieved an effective improvement in luminescence performance. Furthermore, directional luminescence was obtained through a microstructure design. This study provides a feasible path for using 2D nanomaterials in high-performance, flexible wearable devices.

Carboxylated cellulose composite film fabricated via layer‐by‐layer self‐sssembly for thermal management material with ultra‐high thermal conductivity

“…However, with the increase of PDA‐Ni@GNS content, PDA‐Ni@GNS were self‐assembled into a lamellar stack structure between CNF‐C, and the presence of Ni nanoparticles on the surface of GNS helped to increase the fiber resistance, improving the mechanical properties of the CNF‐C/PDA‐Ni@GNS composite film. In addition, there existed hydrogen bonds between the PDA on the Ni@GNS surface and CNF‐C, and the fiber movement under external force was considerably minimized 18 . This was also the reason why the elastic modulus of the CNF‐C/PDA‐Ni@GNS composite films increased with the increase of PDA‐Ni@GNS content.…”

“…(A) Comparison of in‐plane TCs of samples W0–W5 and respective increase factors; (B) schematic of the thermally conductive path established in the composite films; (C) the in‐plane TCs in this study were compared with those reported in existing literature 15,18,19,37 ; (D) linear fitting curve for ITR; (E) ITIs of W0, W1, W4 (from left to right) strip samples; (F) LED heat dissipation curves of W4 and CG; (G) ITIs of the temperature rise and cooling of LED lamp using W4 and CG; (H) picture of computer CPU with W4 attached; (I) ITIs of the CPU on motherboard when using W0–W5 and CG as cooling materials, respectively; (J) CPU rise and drop figure when W1, W4 and CG were used as thermal management materials.…”

“…In addition, there existed hydrogen bonds between the PDA on the Ni@GNS surface and CNF-C, and the fiber movement under external force was considerably minimized. 18 This was also the reason why the elastic modulus of the CNF-C/PDA-Ni@GNS composite films increased with the increase of PDA-Ni@GNS content. As shown in Figure 4C, sample W4 has quite good mechanical properties.…”

“…11 Graphene has been widely used and concerned because of its excellent TC and low density. 16,17 Zhi et al 18 used magnetic fields to regulate the orientation and distribution of graphene in cellulose paper, so that graphene forms an interconnected network structure in a composite film. Chu et al 19 prepared composite films with excellent layered structure based upon MXene, GNPs and cellulose nanofibers (CNF) by vacuum-assisted filtration technology.…”