The Special Issue of
, "Highly Thermal Conductive Nanocomposites", focuses on the application of different types of thermal conductivity nanocomposites in thermal management ....
Owing to the growing heat removal issue of modern electronic devices, polymer composites with high thermal conductivity have drawn much attention in the past few years. However, a traditional method ...to enhance the thermal conductivity of the polymers by addition of inorganic fillers usually creates composite with not only limited thermal conductivity but also other detrimental effects due to large amount of fillers required. Here, novel polymer composites are reported by first constructing 3D boron nitride nanosheets (3D‐BNNS) network using ice‐templated approach and then infiltrating them with epoxy matrix. The obtained polymer composites exhibit a high thermal conductivity (2.85 W m−1 K−1), a low thermal expansion coefficient (24–32 ppm K−1), and an increased glass transition temperature (Tg) at relatively low BNNSs loading (9.29 vol%). These results demonstrate that this approach opens a new avenue for design and preparation of polymer composites with high thermal conductivity. The polymer composites are potentially useful in advanced electronic packaging techniques, namely, thermal interface materials, underfill materials, molding compounds, and organic substrates.
Polymer composites are fabricated by constructing 3D boron nitride nanosheet (3D‐BNNS) networks using an ice‐templated approach. The polymer composites exhibit a high thermal conductivity, low coefficient of thermal expansion, and an increased glass transition temperature at relatively low BNNS loading (9.29 vol%). This approach finds uses in the preparation of the polymer composites with high thermal conductivity.
Enhancing the thermal conductivity of polymers is important for their critical applications in all heat exchangers and electronic packaging. However, owing to the existence of interfacial thermal ...resistance (ITR), the overall thermal conductivity of the polymer composites cannot meet the requirements of the electronics industry. Here, we propose an approach to decreasing the ITR by both improving the contact area and the interconnection between fillers. An increase in out-of-plane thermal conductivity (0.804 W m−1 K−1) is observed in the silver nanoparticles (AgNPs)-boron nitride nanosheet (BNNS)/silver nanowires (Ag NW)/epoxy composites, which is 2.4 times higher than that of the BNNS/epoxy composites. Fitting the measured thermal conductivity of composites with Foygel model indicates that ITR can be reduced effectively when the contact and the interactions of the fillers is optimized. The proposed design methodology here potentially paves the way for designing and preparing higher thermal conductive materials in the future.
Lateral WS2–MoS2 heterostructures
are synthesized by a shortcut one‐step growth recipe with low‐cost and soluble salts. The 2D spatial distributions of the built‐in potential and the related electric ...field of the lateral WS2–MoS2 heterostructure are quantitatively analyzed by scanning Kelvin probe force microscopy revealing the fundamental attributes of the lateral heterostructure devices.
Wearable strain sensors with excellent stretchability and sensitivity have emerged as a very promising field which could be used for human motion detection and biomechanical systems, etc. ...Three-dimensional (3D) graphene foam (GF) has been reported before for high-performance strain sensors, however, some problems such as high cost preparation, low sensitivity, and stretchability still remain. In this paper, we report a highly stretchable and sensitive strain sensor based on 3D GF and polydimethylsiloxane (PDMS) composite. The GF is prepared by assembly process from graphene oxide via a facile and scalable method and possesses excellent mechanical property which facilitates the infiltration of PDMS prepolymer into the graphene framework. The as-prepared strain sensor can be stretched as high as 30% of its original length and the gauge factor of this sensor is as high as 98.66 under 5% of applied strain. Moreover, the strain sensor shows long-term stability in 200 cycles of stretching-relaxing. Implementation of the device for monitoring the bending of elbow and finger results in reproducibility and various responses in the form of resistance change. Thus, the developed strain sensors exhibit great application potential in fields of biomechanical systems and human-interactive applications.
Rapidly increasing packaging density of electronic devices puts forward higher requirements for thermal conductivity of glass fibers reinforced polymer (GFRP) composites, which are commonly used as ...substrates in printed circuit board. Interface between fillers and polymer matrix has long been playing an important role in affecting thermal conductivity. In this paper, the effect of interfacial state on the thermal conductivity of functionalized Al2O3 filled GFRP composites was evaluated. The results indicated that amino groups-Al2O3 was demonstrated to be effective filler to fabricate thermally conductive GFPR composite (1.07W/mK), compared with epoxy group and graphene oxide functionalized Al2O3. It was determined that the strong adhesion at the interface and homogeneous dispersion of filler particles were the key factors. Moreover, the effect of interfacial state on dielectric and thermomechanical properties of GFRP composites was also discussed. This research provides an efficient way to develop high-performance GFRP composites with high thermal conductivity for integrated circuit packaging applications.
High-performance thermal management materials are essential in miniaturized, highly integrated, and high-power modern electronics for heat dissipation. In this context, the large interface thermal ...resistance (ITR) that occurs between fillers and the organic matrix in polymer-based nanocomposites greatly limits their thermal conductive performance. Herein, through-plane direction aligned three-dimensional (3D) MXene/silver (Ag) aerogels are designed as heat transferring skeletons for epoxy nanocomposites. Ag nanoparticles (NPs) were in situ decorated on exfoliated MXene nanosheets to ensure good contact, and subsequent welding of ice-templated MXene/Ag nanofillers at low temperature of ∼200 °C reduced contact resistance between individual MXene sheets. Monte Carlo simulations suggest that thermal interficial resistance (R 0) of the MXene/Ag–epoxy nanocomposite was 4.5 × 10–7 m2 W–1 K–1, which was less than that of the MXene–epoxy nanocomposite (R c = 5.2 × 10–7 m2 W–1 K–1). Furthermore, a large-scale atomic/molecular massively parallel simulator was employed to calculate the interfacial resistance. It was found that R MXene = 2.4 × 10–9 m2 K W–1, and R MXene‑Ag = 2.0 ×10–9 m2 K W–1, respectively, indicating that the Ag NP enhanced the interfacial heat transport. At a relatively low loading of 15.1 vol %, through-plane thermal conductivity reached a value as high as 2.65 W m–1 K–1, which is 1225 % higher than that of pure epoxy resin. Furthermore, MXene/Ag–epoxy nanocomposite film exhibits an impressive thermal conductive property when applied on a Millet 8 and Dell computer for heat dissipation.
Conventional polymer composites normally suffer from undesired thermal conductivity enhancement which has hampered the development of modern electronics as they face a stricter heat dissipating ...requirement. It is still challenging to achieve satisfactory thermal conductivity enhancement with reasonable mechanical properties. Herein, we present a three-dimensional (3D), lightweight, and mechanically strong boron nitride (BN)-silicon carbide (SiC) skeleton with aligned thermal pathways via the combination of ice-templated assembly and high-temperature sintering. The sintering has introduced atomic-level coupling at the BN-SiC junction which contributes to efficient phonon transport via the newly formed borosilicate glass BC x N3–x (0 ≤ x ≤ 3) and SiC x N4–x (0 ≤ x ≤ 4) phases, leading to much lower interfacial thermal resistance. Thus, the obtained BN-SiC skeleton shows satisfactory thermal performance. The prepared 3D BN-SiC/polydimethylsiloxane (PDMS) composites exhibit a maximum through-plane thermal conductivity of 3.87 W·m–1·K–1 at a filler loading of only 8.35 vol %. The thermal conductivity enhancement efficiency reaches 220% per 1 vol % filler when compared to pure PDMS matrix, superior to other reported BN skeleton-based composites. The feature of our strategy is to allow the oriented three-dimensional skeleton to be strongly bonded by a sintered ceramic phase instead of polymer-like adhesive, namely, to improve the intrinsic thermal conductivity of the skeleton to the greatest extent. This strategy can be applied to develop novel thermal management materials that are lightweight and mechanically tough that rapidly transfer heat. It represents a new avenue to addressing the heat challenges in traditional electronic products.
With the increasing integration of devices in electronics fabrication, there are growing demands for thermal interface materials (TIMs) with high through-plane thermal conductivity for efficiently ...solving thermal management issues. Graphene-based papers consisting of a layer-by-layer stacked architecture have been commercially used as lateral heat spreaders; however, they lack in-depth studies on their TIM applications due to the low through-plane thermal conductivity (<6 W m–1 K–1). In this study, a graphene hybrid paper (GHP) was fabricated by the intercalation of silicon source and the in situ growth of SiC nanorods between graphene sheets based on the carbothermal reduction reaction. Due to the formation of covalent C–Si bonding at the graphene–SiC interface, the GHP possesses a superior through-plane thermal conductivity of 10.9 W m–1 K–1 and can be up to 17.6 W m–1 K–1 under packaging conditions at 75 psi. Compared with the current graphene-based papers, our GHP has the highest through-plane thermal conductivity value. In the TIM performance test, the cooling efficiency of the GHP achieves significant improvement compared to that of state-of-the-art thermal pads. Our GHP with characteristic structure is of great promise as an inorganic TIM for the highly efficient removal of heat from electronic devices.
Janus transition-metal dichalcogenides (TMDCs) are emerging as special 2D materials with different chalcogen atoms covalently bonded on each side of the unit cell, resulting in interesting ...properties. To date, several synthetic strategies have been developed to realize Janus TMDCs, which first involves stripping the top-layer S of MoS2 with H atoms. However, there has been little discussion on the intermediate Janus MoSH. It is critical to find the appropriate plasma treatment time to avoid sample damage. A thorough understanding of the formation and properties of MoSH is highly desirable. In this work, a controlled H2-plasma treatment has been developed to gradually synthesize a Janus MoSH monolayer, which was confirmed by the TOF-SIMS analysis as well as the subsequent fabrication of MoSSe. The electronic properties of MoSH, including the high intrinsic carrier concentration (∼2 × 1013 cm–2) and the Fermi level (∼ – 4.11 eV), have been systematically investigated by the combination of FET device study, KPFM, and DFT calculations. The results demonstrate a method for the creation of Janus MoSH and present the essential electronic parameters which have great significance for device applications. Furthermore, owing to the metallicity, 2D Janus MoSH might be a potential platform to observe the SPR behavior in the mid-infrared region.
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