Non-covalent modification of boron nitride nanoparticle-reinforced PEEK composite: Thermally conductive, interfacial, and mechanical properties

Improved thermal conductivity and excellent electrical insulation properties of polysiloxane nanocomposite-incorporated functional boron nitride sheets via in situ polymerization

Benefiting from its high thermal conductivity (κ) and superior insulation, the boron nitride nanosheet (BNNS) is widely investigated as a promising filler for thermal nanocomposites. However, poor dispersibility and weak interaction with polymer matrix hinder the further improvement of BNNS-based thermal composites. Here, inspired by side-chain liquid crystal polysiloxane (SCLCP) with good mesomorphic structures, highly thermoconductive nanocomposites prepared via in situ polymerization using SCLCP with 2D BNNS are reported. The surface of BNNS is silanized with γ-(methacryloxy)propyltrimethoxysilane (KH-570) to introduce double bonds (defined as f-BNNS), and it is directly linked with SCLCP chains during polymerization. Therefore, the alternating stacking of f-BNNS and microscopic ordered structure of SCLCP yielded a high κ of 2.463 W m-1 K-1 at only 30 wt% f-BNNS content, improving dramatically the κ of pure SCLCP by ∼9 times. Further, the volume electrical resistivity reached 2.11 × 1014 Ω cm, which is five orders of magnitude higher than the critical resistance for electrical insulation (109 Ω cm). Also, the f-BNNS/SCLCP composites as thermal management materials decreased the temperature of the LED chip by 17.5 °C, exhibiting superior thermal management performance. Along with high κ and excellent electrical resistance, this type of nanocomposites displays great advantages in thermal properties for electronic packaging and thermal management of electronics.

A Malleable Composite Dough with Well-Dispersed and High-Content Boron Nitride Nanosheets

Aggregation of two-dimensional (2D) nanosheet fillers in a polymer matrix is a prevalent problem when the filler loading is high, leading to degradation of physical and mechanical properties of the composite. To avoid aggregation, a low-weight fraction of the 2D material (<5 wt %) is usually used to fabricate the composite, limiting performance improvement. Here, we develop a mechanical interlocking strategy where well-dispersed high filling content (up to 20 wt %) of boron nitride nanosheets (BNNSs) can be incorporated into a polytetrafluoroethylene (PTFE) matrix, resulting in a malleable, easy-to-process and reusable BNNS/PTFE composite dough. Importantly, the well-dispersed BNNS fillers can be rearranged into a highly oriented direction due to the malleable nature of the dough. The resultant composite film has a high thermal conductivity (4408% increase), low dielectric constant/loss, and excellent mechanical properties (334%, 69%, 266%, and 302% increases for tensile modulus, strength, toughness, and elongation, respectively), making it suitable for thermal management applications in the high-frequency areas. The technique is useful for the large-scale production of other 2D material/polymer composites with a high filler content for different applications.

Achieving High Thermal Conductivity and Satisfactory Insulating Properties of Elastomer Composites by Self-Assembling BN@GO Hybrids

With increasing heat accumulation in advanced modern electronic devices, dielectric materials with high thermal conductivity (λ) and excellent electrical insulation have attracted extensive attention in recent years. Inspired by mussel, hexagonal boron nitride (hBN) and graphene oxide (GO) are assembled to construct mhBN@GO hybrids with the assistance of poly(catechol-polyamine). Then, mhBN@GO hybrids are dispersed in carboxy nitrile rubber (XNBR) latex via emulsion coprecipitation to form elastomer composites with a high λ and satisfactory insulating properties. Thanks to the uniform dispersion of mhBN@GO hybrids, the continuous heat conduction pathways exert a significant effect on enhancing the λ and decreasing the interface thermal resistance of XNBR composites. In particular, the λ value of 30 vol% mhBN@GO/XNBR composite reaches 0.4348 W/(m·K), which is 2.7 times that of the neat XNBR (0.1623 W/(m·K)). Meanwhile, the insulating hBN platelets hinder the electron transfer between adjacent GO sheets, leading to satisfactory electrical insulation in XNBR composites, whose AC conductivity is as low as 10^-10 S/cm below 100 Hz. This strategy opens up new prospects in the assembly of ceramic and carbonaceous fillers to prepare dielectric elastomer composites with high λ and satisfactory electrical insulation, making them promising for modern electrical systems.

Interfacial Engineering Methods in Thermoplastic Composites: An Overview

The paper critically analyzed different interfacial enhancing methods used in thermoplastic composites. Although the absence of cross-linked polymer chains and chemical bonds on solidification enables the thermoplastics to be remelted, it creates weak interfacial adhesion between fibre reinforcements and the thermoplastic matrix. The weak fibre-matrix interface bonding reduces the efficiency with which the applied load can be transferred between these composite constituents, causing the composite to fail prematurely. Their need for high-temperature processing, poor compatibility with other polymer matrices, and relatively high viscosity render thermoplastics challenging when used to manufacture composite laminates. Therefore, various methods, including nanoparticles, changing the polarity of the fibre surface by plasma etching, chemical treatment with ozone, or an oxidative attack at the fibre surface, have been applied to improve the fibre/matrix bonding in thermoplastic composites. The fabrication steps followed in these techniques, their progress in research, and the associated toughening mechanisms are comprehensively discussed in this paper. The effect of different fibre-matrix interfacial enhancement methods on the mechanical properties of thermoplastic composites is also deliberated.

Recent Advances on High-Performance Polyaryletherketone Materials for Additive Manufacturing

Polyaryletherketone (PAEK) is emerging as an important high-performance polymer material in additive manufacturing (AM) benefiting from its excellent mechanical properties, good biocompatibility, and high-temperature stability. The distinct advantages of AM facilitate the rapid development of PAEK products with complex customized structures and functionalities, thereby enhancing their applications in various fields. Herein, the recent advances on AM of high-performance PAEKs are comprehensively reviewed, concerning the materials properties, AM processes, mechanical properties, and potential applications of additively manufactured PAEKs. To begin, an introduction to fundamentals of AM and PAEKs, as well as the advantages of AM of PAEKs is provided. Discussions are then presented on the material properties, AM processes, processing-matter coupling mechanism, thermal conductivity, crystallization characteristics, and microstructures of AM-processed PAEKs. Thereafter, the mechanical properties and anisotropy of additively manufactured PAEKs are discussed in depth. Their representative applications in biomedical, aerospace, electronics, and other fields are systematically presented. Finally, current challenges and possible solutions are discussed for the future development of high-performance AM polymers.

Thermally Conductive and Electrically Insulated Silicone Rubber Composites Incorporated with Boron Nitride−Multilayer Graphene Hybrid Nanofiller

Thermally conductive and electrically insulating composites are important for the thermal management of new generation integrated and miniaturized electronic devices. A practical and eco−friendly electrostatic self−assembly method was developed to prepare boron nitride−multilayer graphene (BN−MG) hybrid nanosheets. Then, BN−MG was filled into silicone rubber (SR) to fabricate BN−MG/SR composites. Compared with MG/SR composites with the same filler loadings, BN−MG/SR composites exhibit dramatically enhanced electrical insulation properties while still maintaining excellent thermal conductivity. The BN−MG/SR with 10 wt.% filler loading shows a thermal conductivity of 0.69 W·m⁻¹·K⁻¹, which is 475% higher than that of SR (0.12 W·m⁻¹·K⁻¹) and only 9.2% lower than that of MG/SR (0.76 W·m⁻¹·K⁻¹). More importantly, owing to the electron blocking effect of BN, the electron transport among MG sheets is greatly decreased, thus contributing to the high−volume resistivity of 4 × 10¹¹ Ω cm for BN−MG/SR (10 wt.%), which is fourorders higher than that of MG/SR (2 × 10⁷ Ω·cm). The development of BN−MG/SR composites with synergetic properties of high thermal conductivity and satisfactory electrical insulation is supposed to be a promising candidate for practical application in the electronic packaging field.

The State-Of-The-Art Functionalized Nanomaterials for Carbon Dioxide Separation Membrane

Nanocomposite membrane (NCM) is deemed as a practical and green separation solution which has found application in various fields, due to its potential to delivery excellent separation performance economically. NCM is enabled by nanofiller, which comes in a wide range of geometries and chemical features. Despite numerous advantages offered by nanofiller incorporation, fabrication of NCM often met processing issues arising from incompatibility between inorganic nanofiller and polymeric membrane. Contemporary, functionalization of nanofiller which modify the surface properties of inorganic material using chemical agents is a viable approach and vigorously pursued to refine NCM processing and improve the odds of obtaining a defect-free high-performance membrane. This review highlights the recent progress on nanofiller functionalization employed in the fabrication of gas-separative NCMs. Apart from the different approaches used to obtain functionalized nanofiller (FN) with good dispersion in solvent and polymer matrix, this review discusses the implication of functionalization in altering the structure and chemical properties of nanofiller which favor interaction with specific gas species. These changes eventually led to the enhancement in the gas separation efficiency of NCMs. The most frequently used chemical agents are identified for each type of gas. Finally, the future perspective of gas-separative NCMs are highlighted.

Tailoring the CO2-selectivity of interfacial polymerized thin film nanocomposite membrane via the barrier effect of functionalized boron nitride

Membrane-based separation is an appealing solution to mitigate CO₂ emission sustainably due to its energy efficiency and environmental friendliness. Attributed to its excellent separation endowed by nanomaterial incorporation, nanocomposite membrane is rigorously developed. This study explored the feasibility of boron nitride (BN) embedment and changes to formation mechanism of ultrathin selective layer of thin film nanocomposite (TFN) are investigated. The effects of amine-functionalization on nanosheet-polymer interaction and CO₂ separation performance are also identified. Participation of nanosheets during interfacial polymerization reduced the crosslinking of selective layer, hence, improved TFN permeance while the formation of contorted diffusion paths by the nanosheets favors transport of small gases. Amine-functionalization enhanced the nanosheet-polymer interaction and elevated the membrane affinity towards CO₂ which led to enhanced CO₂ selectivity. The best TFN prepared in this study exhibited 37% and 20% increment in permeability and selectivity, respectively with respect to neat thin film composite (TFC). It is found that the CO₂ separation performance of BN incorporated TFN is on par with many non-porous nanosheet-incorporated TFNs reported in literatures. The transport and barrier effects of BN and functionalized BN are discussed in detail to provide further insights into the development of commercially attractive CO₂ selective TFN membranes.

Recent Advances in Preparation, Mechanisms, and Applications of Thermally Conductive Polymer Composites: A Review

At present, the rapid accumulation of heat and the heat dissipation of electronic equipment and related components are important reasons that restrict the miniaturization, high integration, and high power of electronic equipment. It seriously affects the performance and life of electronic devices. Hence, improving the thermal conductivity of polymer composites (TCPCs) is the key to solving this problem. Compared with manufacturing intrinsic thermally conductive polymer composites, the method of filling the polymer matrix with thermally conductive fillers can better-enhance the thermal conductivity (λ) of the composites. This review starts from the thermal conduction mechanism and describes the factors affecting the λ of polymer composites, including filler type, filler morphology and distribution, and the functional surface treatment of fillers. Next, we introduce the preparation methods of filled thermally conductive polymer composites with different filler types. In addition, some commonly used thermal-conductivity theoretical models have been introduced to better-analyze the thermophysical properties of polymer composites. We discuss the simulation of λ and the thermal conduction process of polymer composites based on molecular dynamics and finite element analysis methods. Meanwhile, we briefly introduce the application of polymer composites in thermal management. Finally, we outline the challenges and prospects of TCPCs.