Thermally Conductive Anticorrosive Epoxy Nanocomposites with Tannic Acid-Modified Boron Nitride Nanosheets

Effective role of tannic acid in the fabrication of hydrophobic, oleophilic, antibacterial, boron nitride/chlorobutyl rubber nanocomposite for reusable protective clothing and oil-water separation

Boron Nitride (h-BN) possesses unique qualities like increased thermal conductivity, non-toxic nature, and environmental friendliness; hence, it is a good reinforcing agent for chlorobutyl rubber (CIIR). Tannic acid (TA) holds excellent bio-functional properties and is considered as an exceptional bio-exfoliating agent. Hence, in this study, we have utilized the bio-exfoliating ability of TA to exfoliate h-BN and evaluate its efficiency in reinforcing the CIIR matrix. Results demonstrate the exceptional role of tannic acid in imparting multifunctionality to chlorobutyl rubber. CIIR matrix introduced with h-BN:TA (h-BN:TA/CIIR) display excellent mechanical performance due to the reinforcing effect shown by excess TA in addition to the exfoliating effect. In addition, h-BN:TA/CIIR composite exhibited superior antimicrobial activity against S. aureus. The retention of thermal decontamination efficiency of the composites with increase in the number of cycles ensures their promising application in the field of reusable gloves and chemical protective clothing. The exfoliated filler created a tortuous path inside the matrix which prevents the permeation of solvent. Hence the work intends to synergize the hydrophobic nature of h-BN, exfoliating capacity of TA and the barrier abilities of CIIR for the adsorption of oil from oil-water mixture and portrays the future of the trio in water purification.

The Enhancement of the Thermal Conductivity of Epoxy Resin Reinforced by Bromo-Oxybismuth

With the gradual miniaturization of electronic devices, the thermal conductivity of electronic components is increasingly required. Epoxy (EP) resins are easy to process, exhibit excellent electrical insulation properties, and are light in weight and low in cost, making them the preferred material for thermal management applications. In order to endow EPs with better dielectric and thermal conductivity properties, bromo-oxygen-bismuth (BiOBr) prepared using the hydrothermal method was used as a filler to obtain BiOBr/EP composites, and the effect of BiOBr addition on the properties of the BiOBr/EP composites was also studied. The results showed that the addition of a small amount of BiOBr could greatly optimize the dielectric properties and thermal conductivity of EP resin, and when the content of BiOBr was 0.75 wt% and 1.00 wt%, the dielectric properties and thermal conductivity of the composite could reach the optimum, respectively. The high dielectric constant and excellent thermal conductivity of BiOBr/EP composites are mainly due to the good layered structure of BiOBr, which can provide good interfacial polarization and thermal conductivity.

Self-assembled boron nitride nanosheet-based aerogels as support frameworks for efficient thermal energy storage phase change materials

Phase change materials (PCMs) are promising in many fields related to energy utilization and thermal management. However, the low thermal conductivity and poor shape stability of PCMs restrict their direct thermal energy conversion and storage. The desired properties for PCMs are not only high thermal conductivity and excellent shape stability, but also high latent heat retention. In this study, the boron nitride nanosheets (BNNSs) were bridged by small amounts of GO nanosheets and successfully self-assembled into BNNS/rGO (BG) aerogels by hydrothermal and freeze-drying processes. The BG aerogels with interlaced macro-/micro-pores have been proven to be ideally suited as support frameworks for encapsulating polyethylene glycol (PEG). The obtained composite PCMs exhibit high thermal conductivity (up to 1.12 W m-1 K-1), excellent shape stability (maintain at 90 °C for 10 min), and high latent heat (187.2 J g-1) with a retention of 97.3% of the pure PEG, presenting great potential applications in energy storage systems and thermal management of electronic devices.

2D hexagonal boron nitride (h-BN) nanosheets in protective coatings: A literature review

The layered 2D hexagonal boron nitride (h-BN) nanosheets (BNNSs) have received significant attention as effective fillers for composite protective coatings in anti-corrosion, anti-oxidation and anti-wear applications. Vapour deposited h-BN mono/multilayers are related classes well-recognized as protective thin films and coatings. This review comprehensively accounts for the research and development of BNNSs in protective coatings. Chemical vapour deposited (CVD) BN thin films and exfoliated BNNSs-incorporated composite polymer coatings are primarily discussed. Inorganic and nanocarbon-based composite coatings are also covered. Future research potentials are presented.

Cerium Methacrylate Assisted Preparation of Highly Thermally Conductive and Anticorrosive Multifunctional Coatings for Heat Conduction Metals Protection

Preparing polymeric coatings with well corrosion resistance and high thermal conductivity (TC) to prolong operational life and ensure service reliability of heat conductive metallic materials has long been a substantive and urgent need while a difficult task. Here we report a multifunctional epoxy composite coating (F-CB/CEP) by synthesizing cerium methacrylate and ingeniously using it as a novel curing agent with corrosion inhibit for epoxy resin and modifier for boron nitride through "cation-π" interaction. The prepared F-CB/CEP coating presents a high TC of 4.29 W m-1 K-1, which is much higher than other reported anti-corrosion polymer coatings and thereby endowing metal materials coated by this coating with outstanding thermal management performance compared with those coated by pure epoxy coating. Meanwhile, the low-frequency impedance remains at 5.1 × 1011 Ω cm2 even after 181 days of immersion in 3.5 wt% NaCl solution. Besides, the coating also exhibits well hydrophobicity, self-cleaning properties, temperature resistance and adhesion. This work provides valuable insights for the preparation of high-performance composite coatings with potential to be used as advanced multifunctional thermal management materials, especially for heat conduction metals protection.

Hygroscopic and cool boron nitride Nanosheets/Regenerated flax fiber material microstructure Dual-Cooling composite fabric

Developing cooling textiles with unidirectional water transport performances and high thermal conductivities is essential for personal thermal and wet comfort in human activities. We report a green, degradable, hygroscopic cooling material and dual-cooling composite fabric (d-CCF). A boron nitride nanosheet/regenerated flax fiber (BNNS/RFF) material with a high thermal conductivity was prepared by dissolving recovered flax fibers with a green, efficient 1-butyl-3-methylimidazole chloride/dimethyl sulfoxide system and adding BNNSs. The 60- wt% BNNS/RFF materials had excellent thermal conductivity and hydrophilicity, the breaking strength reached 120 MPa, and the elongation was 15.8 %. The d-CCF consisted of cool polyester (CPET) yarn (inner layer), CPET/bamboo composite yarn (middle layer), bamboo yarn, and 60- wt% BNNS/RFF (outer layer) with unobstructed heat dissipation and evaporation cooling for effective moisture and thermal management. This d-CCF had distinct advantages, including a high one-way water transport index (468 %), an extremely high evaporation rate (0.3818 g h^-1), inner layer maximum heat flux (0.191 W cm^-2), and outer layer maximum heat flux (0.249 W cm^-2), providing a cooling sensation upon contact. Compared to cotton fabrics, the d-CCF could keep the skin cooler by 2.5 °C. This work provides a strategy to fabricate environmentally friendly BNNS/RFF materials and a facile pathway for cooling textile development for human health management.

Design and enhanced anticorrosion performance of a Zn5Mo2O11·5H2O/h-BN nanocomposite with labyrinth of nanopores

Zinc molybdate (ZMO) is a safe and effective grafting material for anticorrosion. Herein, we reported the synthesis of ZMO/h-BN with the labyrinth of capillary pores owing to the in situ growth of ZMO on flake hexagonal boron nitride (h-BN) using the hydrothermal method. The special morphological structure provided a tortuous path for aggressive species to the steel substrate, which extended and blocked the transmission of aggressive species, enhancing the physical corrosion barrier performance. In addition, the capillary pores of ZMO contributed to the competitive adsorption of Cl^- in an electrolyte and reduced the diffusion of aggressive species, thus further delaying the corrosion process. Moreover, the capture of oxygen by forming a B-O bond with h-BN and the formation of a molybdate passive film are beneficial for the inhibition of cathodic and anodic reactions. As verified by electrochemical impedance spectroscopy (EIS), the anticorrosion performance of ZMO/h-BN coating increased by 49.58% and 130.72% compared with ZMO and epoxy resin (EP) coatings after immersing in a NaCl aqueous solution (3.50 wt%) for 72 h. This coating matrix provides an avenue for molybdate-based corrosion remediation.

Synergistic Effect of Reinforced Multiwalled Carbon Nanotubes and Boron Nitride Nanosheet-Based Hybrid Piezoelectric PLLA Scaffold for Efficient Bone Tissue Regeneration

Electrospun poly(l-lactic acid) nanofibers (PLLANFs) have been receiving considerable attention in bone tissue engineering (BTE) due to their tunable biodegradability and remarkable in vitro and in vivo biocompatibility. However, deterioration in the mechanical strength of PLLANFs during the regeneration process leads to low osteoinductive performances. Additionally, their high hydrophobicity and limited piezoelectric properties have to be addressed concerning BTE. Herein, we report an efficient approach for fabricating high-performance PLLANF hybrid scaffolds for BTE by reinforcing amphiphilic triblock copolymer pluronic F-127 (PL)-functionalized nanofillers (PL-functionalized carboxylated multiwalled carbon nanotubes (PL-cMWCNTs) and PL-functionalized exfoliated boron nitride nanosheets (PL-EBN)). The synergistic reinforcement effect from one-dimensional (1D) electrically conducting PL-cMWCNTs and two-dimensional (2D) piezoelectric PL-EBN was remarkable in PLLANFs, and the obtained PL-Hybrid (PL-cMWCNTs + PL-EBN) reinforced scaffolds have outperformed the mechanical strength, wettability, and piezoelectric performances of pristine PLLANFs. Consequently, in vitro biocompatibility results reveal the enhanced proliferation of MC3T3-E1 cells on PL-Hybrid nanofiber scaffolds. Furthermore, the ALP activity, ARS staining, and comparable osteogenic gene expression results demonstrated significant osteogenic differentiation of MC3T3-E1 cells on PL-Hybrid nanofiber scaffolds than on the pristine PLLANF scaffold. Thus, the reported approach for constructing high-performance piezoelectric biodegradable scaffolds for BTE by the synergistic effect of PL-cMWCNTs and PL-EBN holds great promise in tissue engineering applications.

Natural leather based gamma-ray shielding materials enabled by the coordination of well-dispersed Bi3+/Ba2+ ions and RE2O3 coating

Gamma rays is widely used in modern science and technology, but it may cause health damage to practitioners. In the present study, natural composites based on leather and high-Z elements (atomic number ≥ 56) were fabricated and used as gamma rays shielding materials. These shielding materials were prepared by coating rare earth nanoparticles (Er2O3 or La2O3) onto the surface of natural leather, which was first impregnated with Bi3+ and Ba2+. Results show that the attenuation efficiency of the prepared Er1.31Bi5.46-NL (1.31 and 5.46 mmol cm−3 loaded elements) with thickness of 3.2 mm was 61.57% for incident rays at 121.78 keV (152Eu) and reached 96.4% in the incident of 59.5 keV (241Am), which is comparable to that of 0.25-mm lead plate (54.54 mmol cm−3). In addition, these natural-leather-based shielding materials exhibited low density (approximately 1/10 of Pb), high strength and wearable behaviors.

Graphical abstract

Vertically Aligned Silicon Carbide Nanowires/Boron Nitride Cellulose Aerogel Networks Enhanced Thermal Conductivity and Electromagnetic Absorbing of Epoxy Composites

With the innovation of microelectronics technology, the heat dissipation problem inside the device will face a severe test. In this work, cellulose aerogel (CA) with highly enhanced thermal conductivity (TC) in vertical planes was successfully obtained by constructing a vertically aligned silicon carbide nanowires (SiC NWs)/boron nitride (BN) network via the ice template-assisted strategy. The unique network structure of SiC NWs connected to BN ensures that the TC of the composite in the vertical direction reaches 2.21 W m^-1 K^-1 at a low hybrid filler loading of 16.69 wt%, which was increased by 890% compared to pure epoxy (EP). In addition, relying on unique porous network structure of CA, EP-based composite also showed higher TC than other comparative samples in the horizontal direction. Meanwhile, the composite exhibits good electrically insulating with a volume electrical resistivity about 2.35 × 10¹¹ Ω cm and displays excellent electromagnetic wave absorption performance with a minimum reflection loss of - 21.5 dB and a wide effective absorption bandwidth (< - 10 dB) from 8.8 to 11.6 GHz. Therefore, this work provides a new strategy for manufacturing polymer-based composites with excellent multifunctional performances in microelectronic packaging applications.