Ultra-Stiff Graphene Foams as Three-Dimensional Conductive Fillers for Epoxy Resin

Flexible Sensors Based on Conductive Polymer Composites

Elastic polymer-based conductive composites (EPCCs) are of great potential in the field of flexible sensors due to the advantages of designable functionality and thermal and chemical stability. As one of the popular choices for sensor electrodes and sensitive materials, considerable progress in EPCCs used in sensors has been made in recent years. In this review, we introduce the types and the conductive mechanisms of EPCCs. Furthermore, the recent advances in the application of EPCCs to sensors are also summarized. This review will provide guidance for the design and optimization of EPCCs and offer more possibilities for the development and application of flexible sensors.

A Brief Overview on Epoxies in Electronics: Properties, Applications, and Modifications

This paper offers a short overview of epoxy resins, encompassing their diverse characteristics, variants, chemical modifications, curing processes, and intriguing electrical properties. Epoxies, valued for their multifunctional attributes, serve as fundamental materials across industries. In the realm of dielectric strength, epoxy resins play a crucial role in electrical insulation. This paper discusses the mechanisms governing dielectric breakdown, strategies to enhance dielectric strength, and the impact of various fillers and additives on insulation performance. Through an exploration of recent research and advancements, this paper delves into the spectrum of epoxy properties, the array of subspecies and variants, their chemical adaptability, and the intricacies of curing. The examination of electrical resistance and conductivity, with a focus on their frequency-dependent behavior, forms a pivotal aspect of the discussion. By shedding light on these dimensions, this review provides a concise yet holistic understanding of epoxies and their role in shaping modern materials science.

Recent Progress on Multifunctional Thermally Conductive Epoxy Composite

In last years, the requirements for materials and devices have increased exponentially. Greater competitiveness; cost and weight reduction for structural materials; greater power density for electronic devices; higher design versatility; materials customizing and tailoring; lower energy consumption during the manufacturing, transport, and use; among others, are some of the most common market demands. A higher operational efficiency together with long service life claimed. Particularly, high thermally conductive in epoxy resins is an important requirement for numerous applications, including energy and electrical and electronic industry. Over time, these materials have evolved from traditional single-function to multifunctional materials to satisfy the increasing demands of applications. Considering the complex application contexts, this review aims to provide insight into the present state of the art and future challenges of thermally conductive epoxy composites with various functionalities. Firstly, the basic theory of thermally conductive epoxy composites is summarized. Secondly, the review provides a comprehensive description of five types of multifunctional thermally conductive epoxy composites, including their fabrication methods and specific behavior. Furthermore, the key technical problems are proposed, and the major challenges to developing multifunctional thermally conductive epoxy composites are presented. Ultimately, the purpose of this review is to provide guidance and inspiration for the development of multifunctional thermally conductive epoxy composites to meet the increasing demands of the next generation of materials.

Cellulose-based sponge@ZIF-8 from waste straws for water disinfection

In this study, zeolitic imidazolate framework-8 (ZIF-8) nanoparticles can be readily in situ generated on the skeleton surface throughout the entire structure of cellulose-based sponges obtained from waste corn straws via a hydrothermal process. Taking natural corn straws as the basic ingredient, the Water Cellulose-based Sponge@ZIF-8 (WCSZ) composite inherits the highly porous structure of straws, which is beneficial for the movement of H2O molecules in both horizontal and vertical directions. A robust H-bond topological network is weaved between abundant hydroxyl groups of the corn straw cell wall matrix and H2O molecules in the honeycomb cellular structure. Based on the topological network, the WCSZ composite maintains sufficient mechanical compressibility and elasticity, which could sustain repeated squeezing without structural failure. The WCSZ composite can not only bear a compressive strain as high as 60% but also completely recover its original height after the load is removed, exhibiting excellent mechanical property. More importantly, the WCSZ composite also presents exceptional antibacterial activities after ZIF-8 nanoparticles were introduced (antibacterial rate: 99.9%). Consequently, the WCSZ composite is an ideal candidate for highly efficient elimination of bacteria as the reusable water treatment material.

Tunable Hybridized Morphologies Obtained through Flash Joule Heating of Carbon Nanotubes

Hybrid carbon nanomaterials, such as those that incorporate carbon nanotubes into graphene sheets, have been found to display interesting mechanical and electrical properties because of their covalent bonding and π-π stacking domains. However, synthesis of these hybrid materials is limited by the high energetic cost of techniques like chemical vapor deposition. Here, we demonstrate the solvent- and gas-free synthesis of a 2D carbon nanotube/graphene network through flash Joule heating of pristine carbon nanotubes. The relative proportion of each morphology in the hybrid material can be tuned by varying the pulse time, as confirmed by Raman spectroscopy and microscopy. Triboindentation of epoxy composites made with the hybrid material shows increases of 162% and 64% to the hardness and Young's modulus, respectively, compared with the neat epoxy. These results demonstrate that flash Joule heating can be used to inexpensively convert carbon nanotubes into a hybrid network of nanotubes and graphene for use as an effective reinforcing additive in epoxy composites.

Artificial Nacre Epoxy Nanomaterials Based on Janus Graphene Oxide for Thermal Management Applications

Owing to the development of microelectronics, demands for excellent thermal dissipation materials have substantially increased. Learning from natural nacre, thermally conductive epoxy nanocomposites were prepared based on asymmetrically polydopamine-functionalized Janus graphene oxide (JPGO) scaffolds. The required highly oriented JPGO scaffolds were prepared via the bidirectional freeze-casting method. With the addition of epoxy resin, the resulting nanocomposite reveals anisotropic thermal properties. With the total content of the JPGO scaffold being 0.93 wt %, almost 35 times enhancement of in-plane thermal conductivity (perpendicular to the lamellar structure) (∼5.6 W m^-1 K^-1) has been obtained. The single-side-functionalized JPGO scaffolds play an important role in forming thermal conductive networks for the epoxy nanocomposites. Importantly, the nanocomposites present electrically insulating properties (>10¹⁴ Ω cm). Such high-performance nanocomposites have promising applications for thermal management in electronic devices.

Millefeuille-Inspired Thermally Conductive Polymer Nanocomposites with Overlapping BN Nanosheets for Thermal Management Applications

Increasing power density makes modern electronic devices and power equipment generate excess heat, which greatly restricts the applications of polymeric materials because of their poor thermal conductivity. In the present work, inspired by the structure and production process of millefeuille cakes, we show that electrostatic spraying of boron nitride nanosheets (BNNSs) onto electrospun poly(vinyl alcohol) (PVA) nanofibers can produce highly thermally conductive, electrically insulating, flexible, and lightweight nanocomposites via a scalable method of building a multilayer PVA/BNNS nanonetwork structure. The PVA/BNNS nanocomposites exhibit an ultrahigh in-plane thermal conductivity of 21.4 W/(m·K) at 22.2 vol % BNNS addition, realized by an orientated BNNS network structure with overlapping interconnections. The BNNS networks exhibit low thermal resistance and interfacial heat scattering between BNNSs. Moreover, for heat dissipation applications, the nanocomposites with an overlapping BNNS network show higher efficiency in dissipating hot spots than randomly dispersed BNNS or directly hot-pressed BNNS composites. These PVA/BNNS nanocomposites can be used as high-performance lateral heat spreaders in next-generation thermal management systems.