High Dielectric Performances of Flexible and Transparent Cellulose Hybrid Films Controlled by Multidimensional Metal Nanostructures

Abstract

Various wearable electronic devices have been developed for extensive outdoor activities. The key metrics for these wearable devices are high touch sensitivity and good mechanical and thermal stability of the flexible touchscreen panels (TSPs). Their dielectric constants (k) are important for high touch sensitivities. Thus, studies on flexible and transparent cover layers that have high k with outstanding mechanical and thermal reliabilities are essential. Herein, an unconventional approach for forming flexible and transparent cellulose nanofiber (CNF) films is reported. These films are used to embed ultralong metal nanofibers that serve as nanofillers to increase k significantly (above 9.2 with high transmittance of 90%). Also, by controlling the dimensions and aspect ratios of these fillers, the effects of their nanostructures and contents on the optical and dielectric properties of the films have been studied. The length of the nanofibers can be controlled using a stretching method to break the highly aligned, ultralong nanofibers. These nanofiber-embedded, high-k films are mechanically and thermally stable, and they have better Young's modulus and tensile strength with lower thermal expansion than commercial transparent plastics. The demonstration of highly sensitive TSPs using high-k CNF film for smartphones suggests that this film has significant potential for next-generation, portable electronic devices.

A Deformable and Highly Robust Ethyl Cellulose Transparent Conductor with a Scalable Silver Nanowires Bundle Micromesh

“…Cellulose, an almost inexhaustible and biodegradable biomass with fascinating characteristics and abundant derivatives, has showed great potential as a transparent flexible substrate for future electronics . Considering the mechanical durability and chemical reliability of the micromesh conductors for long‐term use, ethyl cellulose (EC) was employed as substrate for a bendable and foldable transparent conductor.…”

The acquirement of desirable dielectric properties of carbon nanofiber composites based on the controlled crystallization

“…According to the percolation theory, the dielectric constant of the HDPE composites can be dramatically improved due to the addition of the CNFs in the vicinity of percolation threshold. The percolation theory is described into the following equations by the power law 27,28 : dielectric constant of composites. [29][30][31] But in this paper, the interfacial effect between CNFs and HDPE was weak, and the dielectric constant resulting from interfacial polarization effect was not dominated.…”

Preparation of high-permeance ceramic microfiltration membranes using a pore-sealing method

“…7 Some different polymers such as polyvinyl alcohol (PVA), polyvinyl pyrrolidone (PVP) and polyvinyl butyral (PVB) can be used as sacricial phases. [11][12][13] The use of these polymer binders can improve the drying of the wet lm and avoid cracks in the membrane precursor. In this study, we design a pore-sealing method for preparation of high-permeance alumina MF membrane free of any intermediate layers.…”