Chitin Nanofiber Transparent Paper for Flexible Green Electronics

A Combination of Boron Nitride Nanotubes and Cellulose Nanofibers for the Preparation of a Nanocomposite with High Thermal Conductivity

With the current development of modern electronics toward miniaturization, high-degree integration and multifunctionalization, considerable heat is accumulated, which results in the thermal failure or even explosion of modern electronics. The thermal conductivity of materials has thus attracted much attention in modern electronics. Although polymer composites with enhanced thermal conductivity are expected to address this issue, achieving higher thermal conductivity (above 10 W m^-1 K^-1) at filler loadings below 50.0 wt % remains challenging. Here, we report a nanocomposite consisting of boron nitride nanotubes and cellulose nanofibers that exhibits high thermal conductivity (21.39 W m^-1 K^-1) at 25.0 wt % boron nitride nanotubes. Such high thermal conductivity is attributed to the high intrinsic thermal conductivity of boron nitride nanotubes and cellulose nanofibers, the one-dimensional structure of boron nitride nanotubes, and the reduced interfacial thermal resistance due to the strong interaction between the boron nitride nanotubes and cellulose nanofibers. Using the as-prepared nanocomposite as a flexible printed circuit board, we demonstrate its potential usefulness in electronic device-cooling applications. This thermally conductive nanocomposite has promising applications in thermal interface materials, printed circuit boards or organic substrates in electronics and could supplement conventional polymer-based materials.

Crab Chitin-Based 2D Soft Nanomaterials for Fully Biobased Electric Devices

2D nanomaterials have various size/morphology-dependent properties applicable in electronics, optics, sensing, and actuating. However, intensively studied inorganic 2D nanomaterials are frequently hindered to apply in some particular and industrial fields, owing to harsh synthesis, high-cost, cytotoxicity, and nondegradability. Endeavor has been made to search for biobased 2D nanomaterials with biocompatibility, sustainability, and biodegradability. A method of hydrophobization-induced interfacial-assembly is reported to produce an unprecedented type of nanosheets from marine chitin. During this process, two layers of chitin aggregations assemble into nanosheets with high aspect ratio. With super stability and amphiphilicity, these nanosheets have super ability in creating highly stable Pickering emulsions with internal phase up to 83.4% and droplet size up to 140 μm, in analogue to graphene oxide. Combining emulsifying and carbonization can further convert these 2D precursors to carbon nanosheets with thickness as low as ≈3.8 nm. Having biologic origin, conductivity, and dispersibility in various solvents, resultant carbon nanosheets start a new scenario of exploiting marine resources for fully biobased electric devices with sustainability and biodegradability, e.g., supercapacitor, flexible circuits, and electronic sensors. Hybrid films of chitin and carbon nanosheets also offer low-cost and environment-friendly alternative of conductive components desirable in green electronics, wearable electronics, biodegradable circuits, and biologic devices.

New insights and perspectives into biological materials for flexible electronics

Materials based on biological materials are becoming increasingly competitive and are likely to be critical components in flexible electronic devices.

Engineering strategies for chitin nanofibers

Chitin nanofibers are the fundamental building blocks of numerous structural natural materials. From top-down to bottom-up, here we review engineering strategies to produce chitin nanofibers for engineered materials and their applications.

Natural Materials Assembled, Biodegradable, and Transparent Paper-Based Electret Nanogenerator

Developing eco-friendly and low-cost electronics is an effective strategy to address the electronic waste issue. In this study, transparent cellulose nanopaper (T-paper) and polylactic acid (PLA) electret were used to construct a biodegradable and transparent paper-based electret nanogenerator. The nanogenerator could be assembled with paper products to form a self-powered smart packaging system without impairing the appearance, due to the high transparency and desirable output performance. Furthermore, the self-degradation property in the natural soil of the nanogenerator is demonstrated, indicating that the nanogenerator is recycled and will not pollute the environment. We anticipate that this study will provide new insights to develop eco-friendly power source and paper-based electronics.

Chitin Nanofibers Extracted from Crab Shells in Broadband Visible Antireflection Coatings with Controlling Layer-by-Layer Deposition and the Application for Durable Antifog Surfaces

Reflection from various surfaces of many optical systems, such as photovoltaics and displays, is a critical issue for their performance, and antireflection coatings play a pivotal role in a wide variety of optical technologies, reducing light reflectance loss and hence maximizing light transmission. With the current movement toward optically transparent polymeric media and coatings for antireflection technology, the need for economical and environmentally friendly materials and methods without dependence on shape or size has clearly been apparent. Herein, we demonstrate novel antireflection coatings composed of chitin nanofibers (CHINFs), extracted from crab shell as a biomass material through an aqueous-based layer-by-layer self-assembly process to control the porosity. Increasing the number of air spaces inside the membrane led low refractive index, and precise control of refractive index derived from the stacking of the CHINFs achieved the highest transmittance with investigating the surface structure and the refractive index depending on the solution pH. At a wavelength of 550 nm, the transmittance of the coatings was 96.4%, which was 4.8% higher than that of a glass substrate, and their refractive index was 1.30. Further critical properties of the films were the durability and the antifogging performance derived from the mechanical stability and hydrophilicity of CHINFs, respectively. The present study may contribute to a development of systematically designed nanofibrous films which are suitable for optical applications operating at a broadband visible wavelength with durability and antifog surfaces.

Transparent deoxyribonucleic acid substrate with high mechanical strength for flexible and biocompatible organic resistive memory devices

Biocompatible deoxyribonucleic acid (DNA), with high mechanical strength, was employed as the substrate for a Ag nanowire (Ag NW) pattern and then used to fabricate flexible resistor-type memory devices.