Effect of backbone moiety in diglycidylether-terminated liquid crystalline epoxy on thermal conductivity of epoxy/alumina composite

Highly Thermally Conductive Liquid Crystalline Epoxy Resin Vitrimers with Reconfigurable, Shape-Memory, Photo-Thermal, and Closed-Loop Recycling Performance

The low thermal conductivity, poor toughness, and non-reprocessability of thermosetting epoxy resins severely restrict their applications and sustainable development in flexible electronics. Herein, liquid crystalline epoxy (LCE) and dynamic ester and disulfide bonds are introduced into the cured network of bisphenol A epoxy resin (E-51) to construct highly thermally conductive flexible liquid crystalline epoxy resin (LCER) vitrimers. LCER vitrimers demonstrate adjustable mechanical properties by varying the ratio of LCE to E-51, allowing it to transition from soft to strong. Typically, a 75 mol% LCE to 25 mol% E-51 ratio results in an in-plane thermal conductivity (λ) of 1.27 W m-1 K-1, over double that of pure E-51 vitrimer (0.61 W m-1 K-1). The tensile strength and toughness increase 2.88 folds to 14.1 MPa and 2.45 folds to 20.1 MJ m-3, respectively. Besides, liquid crystalline phase transition and dynamic covalent bonds enable triple shape memory and three-dimensional shape reconstruction. After four reprocessing cycles, λ and tensile strength remain at 94% and 72%, respectively. Integrating carbon nanotubes (CNTs) imparts photo-thermal effect and enables "on" and "off" switch under near-infrared light to LCER vitrimer. Furthermore, the CNTs/LCER vitrimer displays light-induced actuation, self-repairing, and self-welding besides the closed-loop recycling and rapid degradation performance.

High-Performance Organic Aerogels Tailored for Versatile Recycling Approaches: Recycling-Reforming-Upcycling

Organic aerogels are emerging as promising materials due to their versatile properties, rendering them excellent candidates for a variety of applications in the fields of thermal insulation, energy storage, pharmaceuticals, chemical adsorption, and catalysis. However, current aerogel designs rely on cross-linked polymer networks, which lack efficient end-of-use solutions, thereby hindering their overall sustainability. In this study, a facile synthesis of organic aerogels with a unique combination of imine and cyanurate moieties is presented, resulting in high-performance, lightweight insulating materials. The aerogels' structure, ensures mechanical robustness, thermal resistance, and hydrophobicity without additional treatments, crucial for long-term performance. Additionally, in response to the currently unsustainable use of cross-linked polymer materials, the molecular design offers diverse avenues of chemical recycling. These include full depolymerization back into the original monomers, partial network fragmentation producing soluble oligomers that can be promptly employed to fabricate new aerogels, and upcycling of aerogel waste into useful building blocks. This work pioneers a novel approach to material design, emphasizing recyclability as a core feature while maintaining high-performance excellence.

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.

The Investigation of the Effect of Filler Sizes in 3D-BN Skeletons on Thermal Conductivity of Epoxy-Based Composites

Thermally conductive and electrically insulating materials have attracted much attention due to their applications in the field of microelectronics, but through-plane thermal conductivity of materials is still low at present. In this paper, a simple and environmentally friendly strategy is proposed to improve the through-plane thermal conductivity of epoxy composites using a 3D boron nitride (3D-BN) framework. In addition, the effect of filler sizes in 3D-BN skeletons on thermal conductivity was investigated. The epoxy composite with larger BN in lateral size showed a higher through-plane thermal conductivity of 2.01 W/m·K and maintained a low dielectric constant of 3.7 and a dielectric loss of 0.006 at 50 Hz, making it desirable for the application in microelectronic devices.

Dispersing Nanoparticles by Chiral Liquid Crystalline Elastomers for Performance Enhancement of Epoxy Nanocomposites

Epoxy nanocomposites with novel chiral side‐chain liquid crystalline elastomers (CSLCE) as dispersant grafted alumina (Al2O3) nanoparticles are prepared. The CSLCE are grafted onto the surface of Al2O3 by esterification, improving the dispersion of Al2O3 in organics. The side chain of CSLCE is composed of M1 containing a chiral mesogenic unit, a liquid crystal cross‐linking agent M2 containing a nematic mesogenic unit, and M3 containing carboxyl groups, which is because the structures can determine the characteristics of polymers. Optical rotation emerges via chiral mesogenic units in CSLCE, and the liquid crystal cross‐linking agent in the side chain causes the polymer to be linked into chains. The fracture toughness and thermal conductivity of Al2O3‐CSLCE/epoxy nanocomposites are significantly improved due to the good dispersion of Al2O3 nanoparticles in the epoxy and the synergistic interaction between Al2O3 and CSLCE. Meanwhile, the glass transition temperatures and thermal stability are enhanced.