Silver-Nanoparticle-Embedded Hybrid Nanopaper with Significant Thermal Conductivity Enhancement

Boron Nitride-Polymer Composites with High Thermal Conductivity: Preparation, Functionalization Strategy and Innovative Structural Regulation

The escalating thermal challenges posed by increasing power densities in electronic devices emerge as a critical barrier to maintain their sustained and reliable operation. Addressing this issue requires the strategic development of materials with superior thermal conductivity properties to facilitate progress in high-power electronics development. Thermal conductive polymer composites by incorporating ceramic material renowned for their exceptional thermal conductivity adjustability, insulating properties, and moldability, are emerging as a promising solution to this urgent challenge. Hexagonal boron nitride (h-BN) nanomaterials emerge as highly promising candidates for thermal management applications, owing to their exceptional mechanical properties, superior thermal stability, remarkable thermal conductivity coefficients, minimal thermal expansion characteristics, and outstanding chemical inertness. In this work, the progress of ≈10 years on high thermal conductive boron nitride-filled polymer composites is thoroughly summarized. Moreover, strategies for h-BN and other boron nitride nanomaterials-filled polymer composites at synthesis, functionalization, and innovative structural design are discussed in detail. The main challenges and future development of boron nitride-polymer composites in thermal management are also proposed, which will provide meaningful guidance for the design and practical applications of thermal management materials.

A Durable Textile With Advanced Thermal Functions and Electromagnetic Shielding

In the face of increasingly variable cold climates and diverse individual temperature regulation demands, personal thermal management (PTM) textiles with electromagnetic shielding have obtained significant attention. However, the PTM textiles face several challenges, including single heating mode, insufficient durability, and complex preparation processes. Herein, an all-day PTM textile Cotton@PDA/AgNPs (CPANS) with energy-free PRH, energy-saving solar heating, compensatory electrical heating, electromagnetic interference (EMI) shielding, and outstanding durability is fabricated by sequentially growing polydopamine (PDA) and silver nanoparticles (AgNPs) on the cotton fabric (CF). The CPANS exhibits low mid-infrared emissivity (36.6%) and high absorptivity (70.8%), which guarantees the energy-saving heating capability. Moreover, the conductivity of the CPANS is ≈11109 S m-1, enabling an electrical heating temperature of ≈177 °C under a low voltage of 1.1 V and superb EMI shielding effectiveness (≈60 dB). The remarkable adhesive properties of the PDA ensure that the desired durability of the CPANS remains high even after rigorous physical treatments. This innovation shows enormous potential for wearable integrated garments in the future and offers a new ideal for PTM fabrics in the cold.

Silver Nanoparticles: A Comprehensive Review of Synthesis Methods and Chemical and Physical Properties

Recently, silver nanoparticles (NPs) have attracted significant attention for being highly desirable nanomaterials in scientific studies as a result of their extraordinary characteristics. They are widely known as effective antibacterial agents that are capable of targeting a wide range of pathogens. Their distinct optical characteristics, such as their localized surface plasmon resonance, enlarge their utilization, particularly in the fields of biosensing and imaging. Also, the capacity to control their surface charge and modify them using biocompatible substances offers improved durability and specific interactions with biological systems. Due to their exceptional stability and minimal chemical reactivity, silver NPs are highly suitable for a diverse array of biological applications. These NPs are produced through chemical, biological, and physical processes, each of which has distinct advantages and disadvantages. Chemical and physical techniques often encounter issues with complicated purification, reactive substances, and excessive energy usage. However, eco-friendly biological approaches exist, even though they require longer processing times. A key factor affecting the stability, size distribution, and purity of the NPs is the synthesis process selected. This review focuses on how essential it is to choose the appropriate synthesis method in order to optimize the characteristics and use of silver NPs.

Enhancing Mechanical and Antimicrobial Properties of Dialdehyde Cellulose-Silver Nanoparticle Composites through Ammoniated Nanocellulose Modification

Given the widespread prevalence of viruses, there is an escalating demand for antimicrobial composites. Although the composite of dialdehyde cellulose and silver nanoparticles (DAC@Ag1) exhibits excellent antibacterial properties, its weak mechanical characteristics hinder its practical applicability. To address this limitation, cellulose nanofibers (CNFs) were initially ammoniated to yield N-CNF, which was subsequently incorporated into DAC@Ag1 as an enhancer, forming DAC@Ag1/N-CNF. We systematically investigated the optimal amount of N-CNF and characterized the DAC@Ag1/N-CNF using FT-IR, XPS, and XRD analyses to evaluate its additional properties. Notably, the optimal mass ratio of N-CNF to DAC@Ag1 was found to be 5:5, resulting in a substantial enhancement in mechanical properties, with a 139.8% increase in tensile elongation and a 33.1% increase in strength, reaching 10% and 125.24 MPa, respectively, compared to DAC@Ag1 alone. Furthermore, the inhibition zones against Escherichia coli and Staphylococcus aureus were significantly expanded to 7.9 mm and 15.9 mm, respectively, surpassing those of DAC@Ag1 alone by 154.8% and 467.9%, indicating remarkable improvements in antimicrobial efficacy. Mechanism analysis highlighted synergistic effects from chemical covalent bonding and hydrogen bonding in the DAC@Ag1/N-CNF, enhancing the mechanical and antimicrobial properties significantly. The addition of N-CNF markedly augmented the properties of the composite film, thereby facilitating its broader application in the antimicrobial field.

Recent Advances in Metallic Nanostructures-assisted Biosensors for Medical Diagnosis and Therapy

The field of nanotechnology has witnessed remarkable progress in recent years, particularly in its application to medical diagnosis and therapy. Metallic nanostructures-assisted biosensors have emerged as a powerful and versatile platform, offering unprecedented opportunities for sensitive, specific, and minimally invasive diagnostic techniques, as well as innovative therapeutic interventions. These biosensors exploit the molecular interactions occurring between biomolecules, such as antibodies, enzymes, aptamers, or nucleic acids, and metallic surfaces to induce observable alterations in multiple physical attributes, encompassing electrical, optical, colorimetric, and electrochemical signals. These interactions yield measurable data concerning the existence and concentration of particular biomolecules. The inherent characteristics of metal nanostructures, such as conductivity, plasmon resonance, and catalytic activity, serve to amplify both sensitivity and specificity in these biosensors. This review provides an in-depth exploration of the latest advancements in metallic nanostructures-assisted biosensors, highlighting their transformative impact on medical science and envisioning their potential in shaping the future of personalized healthcare.

Production of hybrid AgNPs - TEMPO-mediated oxidation cellulose composite from jackfruit peduncle agro-waste and its thermal management application in electronic devices

The urgent need for eco-friendly and cost-effective cellulose paper substrates in thermal management for biomedical electronic devices has driven the exploration of agro-waste materials. In this study, jackfruit peduncle waste was utilized as a precursor to produce a hybrid of AgNPs-tempo-mediated oxidation cellulose strands (AgNPs-TOCS) through acid hydrolysis, TEMPO oxidation, and an in-situ generation process. The resulting hybrid AgNPs-TOCS composite exhibited a cylindrical cellulose structure with a diameter of 27.3 μm, on which spherical AgNPs with a diameter of 16.3 nm were embedded. This hybrid AgNPs-TOCS displayed an impressive inhibition zone diameter against E. coli bacteria (15.2 nm) and exhibited excellent thermal stability up to 269 °C. Furthermore, the AgNPs-TOCS composite paper substrate was fabricated using non-solvent techniques, and its mechanical, thermal, and electrical properties were investigated. This composite paper substrate exhibits good tensile strength (65 ± 2 MPa), in-plane thermal conductivity (5.8 ± 0.2 W/(m·K)), and electrical resistivity (0.0575 KΩ·m). These findings strongly suggest that this type of composite paper substrate holds promise for applications in thermal management within the field of biomedical electronics.

Thermal Interface Engineering in a 3D-Structured Carbon Framework for a Phase-Change Composite with High Thermal Conductivity

Phase-change materials (PCMs) are promising thermal storage medium for thermal management due to their efficient thermal energy harvesting capabilities. However, the low thermal conductivity (TC) and poor shape stability of PCMs have hindered their practical applications. Construction of an interconnected three-dimensional (3D) heat-conductive structure is an effective way to build phonon conduits and provide PCM confinement. Phonon scattering at the interface is an unavoidable effect that undermines the TC improvement in the PCM composite and necessitates careful engineering. This study focuses on creating a highly thermally conductive 3D carbon-bonded graphite fiber (CBGF) network to enhance the TC of the PCM, with attention especially on thermal interface engineering considering both filler-matrix (F-M) and filler-filler (F-F) interfaces. The composite with an optimized proportion of F-M and F-F interface area achieves the highest TC of 45.48 W·m-1·K-1, which is 188.5 times higher than that of the pure PCM, and a high TC enhancement per volume fraction of the filler (TCEF) of 831% per 1 vol % loading. This also results in an enhanced spatial construction for PCM confinement during the phase change. The results emphasize the significance of interface engineering in creating high-TC and form-stable phase-change composites, providing insightful guidance for rational structural design.

Significantly Enhancing Mechanical and Thermal Properties of Cellulose-Based Composites by Adding Small Amounts of Lysozyme-Modified Graphene Nanoplatelets via Forming Strong Double-Cross-Linked Interface Interactions

Thermally conductive cellulose-based composites have great application potential in the thermal management of portable and wearable electronic devices. In this work, cellulose-based composites with excellent mechanical and thermal properties were developed by using lysozyme-modified graphene nanoplatelets (LmGNP), epichlorohydrin (ECH), and hydrolyzed cellulose via forming strong double-cross-linked interface interactions, including the hydrogen bond network generated between LmGNP and cellulose and the chemical cross-link of ECH. As for the composites containing 8 wt % LmGNP, the in-plane thermal conductivity was 3.341 W·m-1K-1, while the tensile stress was 114.60 MPa, which increased by 297.3 and 146.2%, respectively, compared to pure cellulose. Along with the good stability, insulation, and lightweight properties, the fabricated composites have the potential to become a promising heat dissipation material for wearable electronic devices.

Eco-Friendly Silver Nanoparticles/Chitosan/Poly(vinyl alcohol) Composites Exhibit Remarkable EMI Shielding Capabilities and Outstanding Thermal Conductivities

The integration and miniaturization of contemporary electronics have led to significant challenges in dealing with electromagnetic (EM) radiation and heat accumulation. Despite these issues, achieving high thermal conductivity (TC) and electromagnetic interference (EMI) shielding effectiveness (SE) in polymer composite films remains an exceptionally difficult task. In this work, we used a straightforward in situ reduction process and a vacuum-drying method to successfully prepare a flexible Ag NPs/chitosan (CS)/PVA nanocomposite with three-dimensional (3D) conductive and thermally conductive network architectures. The 3D silver pathways formed by attaching to the chitosan fibers endow the material with simultaneous exceptional TC and EMI capabilities. At a silver concentration of 25 vol %, the TC of Ag NPs/CS/PVA nanocomposites reaches 5.18 W·m^-1·K^-1, exhibiting an approximately 25 times increase compared to CS/PVA composites. The electromagnetic shielding performance of 78.5 dB significantly outperforms the specifications of standard commercial EMI shielding applications by a significant margin. Additionally, Ag NPs/CS/PVA nanocomposites have greatly benefited from microwave absorption (SE_A), effectively impeding the transmission of EM waves and reducing the reflected secondary EM wave pollution. Meanwhile, the composite material still maintains good mechanical properties and bendability. This endeavor helped develop malleable and durable composites that possess superior EMI shielding capabilities and intriguing heat dissipation properties using innovative design and fabrication methods.

High-Performance and Rapid-Response Electrical Heaters Derived from Cellulose Nanofiber/Silver Nanowire Nanopapers for Portable Thermal Management

High-performance electrical heaters with outstanding flexibility, superior portability, and mechanical properties are highly desirable for portable thermal management. However, it is still a huge challenge to simultaneously achieve competent electrical heating performances and excellent mechanical properties. Herein, inspired by the Janus structure, versatile electrical heaters are developed via a sequential assembly followed by a hot-pressing strategy. The elaborately designed Janus structure is composed of a nanofibrillated cellulose (NFC) layer and a partially wrapped silver nanowire (AgNW) skeleton in the NFC substrate. Owing to the perfect introduction of nano-soldered points induced by thermal welding decoration, the resultant NFC/AgNW papers (NAPs) possess great flexibility, excellent mechanical strength (176.75 MPa), extremely low sheet resistance (0.60 Ω/sq), and superior electrical stabilities against mechanical deformations. Moreover, benefitting from these fascinating attributes, the NAP-based electrical heaters exhibit a remarkable heating temperature (∼220 °C), ultrafast electro-thermal response (<10 s), and groundbreaking long-term stability (∼105 °C for >186 h) and repeatability (>20,000 cycles) with low AgNW contents and driving voltages (0.5-5.0 V), which far surpass those of the previously reported and conventional indium tin oxide-based Joule heaters. Impressively, large-area production feasibilities of NAPs are demonstrated and assembled into multifunctional applications, including personal thermal management, healthcare thermotherapy, multifunctional cups, and smart homes, indicating their promising potential for wearable devices, artificial intelligence, and specific heating systems in the fields of aerospace, military, and intelligent life.