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A technique for exfoliating Boron nitride (BN) nanosheets was devised, which was then followed by a laser ablation-fragmentation process to produce lamellar hexagonal Boron nitride nanostructures (h-BNNs). The physicochemical properties of the nanoparticles were analyzed to investigate the effect of laser energy and wavelength in the two-step pre-treatment procedure during BN synthesis. The X-ray diffraction (XRD) patterns showed no impurity phase structures and only primary h-BN reflections were visible. It was discovered that the crystallite h-BNNs size ranged from 11 to 18 nm, and nanosecond laser energy was sufficient to transform BN into h-BNNs and a few nanotubes. Combining laser intensity and wavelength transformed the BN nanoparticle shape from haphazardly arranged platelets to melting-like formations. Fourier Transform infrared (FTIR) spectroscopy confirmed distinct observed changes in the size and melting behavior in the h-BNNs and the sharp absorption peaks which could indicate changes in their optical properties. Morphological characteristics and formation of the hexagonal phase of BN caused variations in optical properties and high-resolution transmission electron microscopy (HRTEM) results. Photoluminescence of h-BNNs was observed in the 250–600 nm range with peak emission at 485 nm. Due to its significant structural disorder, the h-BNNs exhibited a wide emission with a strong luminescence that remained largely continuous after 48 hours, resulting in a distinctive blue hue (470, and 485nm).

An emphasis on the development of lightweight structures in multitudes of engineering applications has broadened the scope for the continual development of fiber-reinforced composites due to their lightweight and superior strength. The current work is aimed to investigate the influence of fillers graphene and hexagonal boron nitride (h-BN) on carbon, Kevlar, and hybrid fabric when they form fiber-reinforced composites. In particular, the properties such as storage modulus, loss modulus, damping factor, and glass transition temperature were determined for various composites to understand the influence of fillers, fabric combinations, and their interaction in synergy. The unique contribution of this work also lies in the inter-correlation of Full width-half Maximum (FWHM) of loss modulus (E") plots to understand the phenomena of abrasive wear. An inhomogeneity factor based on the Cole-Cole plots termed as circularity index was also calculated by using Full Maximum (F.M.) and the FWHM. Carbon, Kevlar, and hybrid fabric mat reinforced epoxy composites, with 0.1, 0.3 & 0.5 wt% loadings of graphene and h-BN were prepared using the hand layup technique. The Dynamic mechanical analysis (DMA) was performed under temperature sweep (30–200°C). The results were analysed to understand the choice of h-BN with Kevlar fabric for applications needing high damping while graphene with carbon fabric for applications needing high tenacity. A hybrid fabric mat offers a balance of damping and tenacity. It was observed that the GC2 composite showed a 49% increment in storage modulus (E'), and GK2 composites showed a 38% increment in loss modulus (E") compared to GC0 and GK0 composites. [ABSTRACT FROM AUTHOR]

In this study, a new stable and powerful hexagonal boron nitride supported N-heterocyclic carbene-palladium(II) complex (h-BN@NHC-Pd) heterogeneous catalyst was designed and synthesized. The structure of the h-BN@NHC-Pd heterogeneous catalyst was characterized by various techniques such as Fourier transform infrared spectra (FT-IR), ultraviolet–visible spectroscopy (UV–Visible), inductively coupled plasma-optical emission spectroscopy (ICP-OES), energy-dispersive X-ray spectroscopy (EDS), field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), thermogravimetric analysis (TGA) and Brunauer–Emmett–Teller surface area analysis (BET). Then catalytic activity of h-BN@NHC-Pd heterogeneous catalyst was studied in the Suzuki–Miyaura cross-coupling reactions between aryl halides and arylboronic acids in aqueous medium at room temperature. The effects of varying solvents, bases, temperature, time and catalytic ratios on the performance of the Suzuki–Miyaura cross-coupling reaction were investigated. Moreover, h-BN@NHC-Pd heterogeneous catalyst could be easily recovered through simple filtration or centrifugation method and could be reused five times without significant loss of its catalytic efficiency. Furthermore, stability of the h-BN@NHC-Pd heterogeneous catalyst after recycling was confirmed through FESEM and FT-IR techniques. The h-BN@NHC-Pd heterogeneous catalyst shows remarkable advantages such as simplicity of operation, excellent yields, short reaction times, heterogeneous nature, easily separable and high stability without leaching. A new stable and powerful hexagonal boron nitride supported N-heterocyclic carbene-palladium(II) complex (h-BN@NHC-Pd) heterogeneous catalyst was designed, synthesized, characterized and catalytic activity was studied in the Suzuki–Miyaura cross-coupling reactions. [ABSTRACT FROM AUTHOR]

Abstract: Phospholipid molecules (PLs) in vivo and graphite, molybdenum disulfide, tungsten disulfide and hexagonal boron nitride (h-BN) in vitro are good examples of frictionless lubricants. PLs and solid materials have the ability to form multi-bilayer or layered structures similar to lamellate solid. It has been confirmed experimentally that PLs as lamellar lubricants protect the surface of joints against wear while acting as frictionless lubricant. An experimental study has been conducted on the friction properties of h-boron nitride on porous non-full journal bearings. The porous non-full journal bearings were a mixture of 97.5wt.% Fe and 2.5wt.% Cu powder, and compressed to a density of 5.9g/cm3. The porosity of non-full journal bearings were15.5 and 27.8wt.% and were impregnated with vaseline and vaseline+5wt.% h-BN. Additionally, the two additives SFR NLGI #2 (or SFR 2522) grease and graphite grease were used for comparison to h-BN. The tribological tests were performed on a four-ball machine under load of 49daN, and a friction tribotester. The above experiment strongly suggested that h-BN has the ability to lubricate under load with very low friction coefficient comparable to phospholipids. Relatively low surface energy and low adhesion between the crystallites are giving the additives low friction coefficient. The results of the experimental studies showed that h-BN as an additive in vaseline possesses friction reducing properties, and excellent anti-wear properties. [Copyright &y& Elsevier]