Search Results (7)

Hexagonal boron nitride (h-BN) and boron nitride nanotubes (BNNTs) are emerging advanced nanomaterials with analogous structures to graphene and carbon nanotubes, respectively. However, little is known about what effect replacing carbon atoms with boron and nitrogen will have on the materials’ safety profile. This study’s aim was to first identify if multi-walled nanotubes of BN could produce a hazard profile similar to that evidenced already for multi-walled carbon nanotubes (MWCNTs) and secondly if the material when present in a sheet-like structure increases or decreases the hazard profile. Fish are aquatic organisms sensitive to boron compounds; however, the potential hazard following exposure to BN and especially when present in such nanostructures has not yet been investigated. An in vitro testing platform consisting of multiple cell lines of the rainbow trout, Oncorhynchus mykiss (RTH-149, RTG-2, RTL-W1 and RTgill-W1), was used in a first-hazard screening approach for cytotoxicity and to gain information on material–cellular interaction. Clear differences were evidenced in material uptake, leading to plasma membrane disruption accompanied with a loss in metabolic activity for BNNTs at lower exposure concentrations compared to h-BN. As in the case of carbon nanotubes, close attention must be given to potential interferences with assays based on optical readouts. Full article

Recent findings have demonstrated that the desalination and purification of contaminated water and the separation of ions and gases, besides solutions to other related issues, may all be achieved with the use of membranes based on artificial nanoporous materials. Before the expensive stages of production and experimental testing, the optimum size and form of membrane nanopores could be determined using computer-aided modeling. The notion that rectangular nanopores created in a multilayered hexagonal boron nitride (h-BN) membrane in a way that results in different inner lining atoms would exhibit unique properties in terms of the water penetration rate is put forth and examined in the current study. Nanopores in boron nitride sheets can be generated with the inner lining of boron atoms (B-edged), nitrogen atoms (N-edged), or both boron and nitrogen atoms (BN-edged). In this study, we compared the three different inner-lined nanopores of boron nitride nanosheets to a comparable-sized graphene nanopore and evaluated the water conduction. Full article

The stacking of two-dimensional atomic-level thickness materials onto hexagonal boron nitride (h-BN) and graphene (Gr) not only significantly enhances their properties, but also exhibits a multitude of exceptional characteristics, promising widespread applications across various fields. Clay minerals hold profound significance in scientific research not only because of their abundance but also because of their application in geology, environmental science, materials science, and biotechnology. We present a study that uses density functional theory (DFT) to analyze the effect on the mechanical properties of lizardite slab-reinforced Gr or h-BN monolayers. In addition to the reference lizardite slab (Liza-2D), six composites were studied: a monolayer of Gr (h-BN) over the octahedral face of a pristine lizardite slab (Liza-Gr1 (Liza-BN1)), a monolayer of Gr (h-BN) under the tetrahedral face of a pristine lizardite slab (Liza-Gr2(Liza-BN2)), and a pristine lizardite slab sandwiched between two Gr (h-BN) monolayers (Liza-Gr3(Liza-BN3)). We observed that reinforcement by Gr or h-BN significantly increased the bulk, Young’s and shear moduli of the composites. Taking into account that the Gr and h-BN sheets interact weakly by van der Waals interactions with the lizardite slab surface, we estimated the Young’s and shear moduli of the composites by the Rule of Mixtures and obtained a reasonable agreement with those from DFT calculations. Full article

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. Full article

Aramid, chemically known as para phenylene terephthalamide or PPD-T, has been widely used in the reinforcement of telecommunication cables, rubber materials (transmission belts, pneumatic belts), ballistic clothing, and frictional materials primarily due to their high tensile resistance, high elastic modulus, and excellent thermal stability (−80–200 °C). These unique properties of aramid originate from its chemical structure, which consists of relatively rigid polymer chains linked by benzene rings and amide bonds (-CO-NH-). Here, in this work inspired by these properties, a heat spreader called Thermal Interface Material (TIM) is developed by synthesizing a resin from scrap aramid fibers. When hexagonal boron nitride (h-BN) as filler is introduced into the as-synthesized aramid resin to form a thin film of thermal sheet (50 μm), an in-plane thermal conductivity as high as 32.973 W/mK is achieved due to the firmly stacked and symmetric arrangement of the h-BN in the resin matrix. Moreover, the influence of h-BN platelet size is studied by fabricating thermal sheets with three different sizes of h-BN (6–7.5 μm, 15–21 μm, and 30–35 μm) in the aramid resin. The results of the study show that as platelet size increases, thermal conductivity increases significantly. Since the resin reported herein is developed out of scrap aramid fibers, the cost involved in the manufacture of the thermal sheet will be greatly lower. As the thermal sheet is designed with h-BN rather than graphene or carbonaceous materials, this high heat spreading sheet can be employed for 5G antenna modules where properties like a low dielectric constant and high electrical insulation are mandated. Full article

Corrosion is a naturally occurring phenomenon and there is continuous interest in the development of new and more protective coatings or films that can be employed to prevent or minimise corrosion. In this review the corrosion protection afforded by two-dimensional graphene is described and discussed. Following a short introduction to corrosion, the application of graphene in the formulation of coatings and films is introduced. Initially, reduced graphene oxide (rGO) and metallic like graphene layers are reviewed, highlighting the issues with galvanic corrosion. Then the more successful graphene oxide (GO), functionalised GO and polymer grafted GO-modified coatings are introduced, where the functionalisation and grafting are tailored to optimise dispersion of graphene fillers. This is followed by rGO coupled with zinc rich coatings or conducting polymers, GO combined with sol-gels, layered double hydroxides or metal organic frameworks as protective coatings, where again the dispersion of the graphene sheets becomes important in the design of protective coatings. The role of graphene in the photocathodic protection of metals and alloys is briefly introduced, while graphene-like emerging materials, such as hexagonal boron nitride, h-BN, and graphitic carbon nitride, g-C₃N₄, are then highlighted. Full article

We carried out molecular dynamics simulations at various temperatures to predict the thermal conductivity and the thermal conductance of graphene and hexagonal boron-nitride (h-BN) thin films. Therefore, several models with six different grain boundary configurations ranging from 33–140 nm in length were generated. We compared our predicted thermal conductivity of pristine graphene and h-BN with previously conducted experimental data and obtained good agreement. Finally, we computed the thermal conductance of graphene and h-BN sheets for six different grain boundary configurations, five sheet lengths ranging from 33 to 140 nm and three temperatures (i.e., 300 K, 500 K and 700 K). The results show that the thermal conductance remains nearly constant with varying length and temperature for each grain boundary. Full article