Hexagonal Boron Nitride Nanoparticles Research Articles

Hexagonal BN/Methylene Blue Heterostructures for Local Photodynamic Therapy of Melanoma

Melanoma is the most aggressive form of skin tumor and leads to a high mortality (5.0–5.6 %) among all cancers. To increase efficiency of its treatment during local photodynamic therapy (PDT), we developed h-BN/n·MB heterostructures based on hexagonal boron nitride (h-BN) nanoparticles (NPs) and adsorbed methylene blue (MB) of various concentrations (n). Heterostructures containing 200 mg of MB per 1 g of h-BN (h-BN/200 MB), after their irradiation with an artificial sunlight source for 30 min, generated 3.7 × 10−2 ± 0.2 × 10−3 μM × μg−1 of reactive oxygen species (ROS) and reduced the viability of A-375 melanoma cells by 90 % after 48 h. The observed levels of oxidative and antitumor activity of the h-BN/200 MB hybrid material significantly exceed those of the individual system components, MB and h-BN. It is shown that MB adsorbed on h-BN NPs possesses enhanced stability and photooxidative activity. Adsorbed MB has almost not the dark phototoxicity inherent in the MB solution and demonstrates enhanced biocompatibility with normal fibroblasts Wi-38. The results demonstrate the promising potential of h-BN/n-MB heterostructures for melanoma PDT.

Synthesis, Microstructural Investigation, and Mechanical Behavior of AA5083/Boron Nitride Nanocomposite

The as‐received aluminum alloy (AA5083) powders (44 μm) and hexagonal boron nitride (BN) nanoparticles (65–75 nm) are used to fabricate AA5083‐BN nanocomposites with varying BN content (0, 3, 6, 9, and 12 wt%). A powder metallurgy solid‐state method is employed, involving ball milling for 20 h at 100 rpm with a ball‐to‐powder mass ratio of 10:1. The processed powders are then consolidated through forging–sintering at 550 °C for 30 min, followed by hot forging at 225 MPa. The microstructure is examined using X‐ray diffraction, scanning electron microscopy, energy‐dispersive X‐ray, transmission electron microscopy, and electron backscatter diffraction to understand the effect of processing variables. The compaction behavior is investigated both experimentally and empirically, revealing a relative green density exceeding 88% at 500 MPa. The empirical models display coefficients of determination (R2 values) exceeding 99% for predicting the compaction behavior. Compression tests on bulk samples show that BN reinforcement significantly enhances ultimate compressive strength, with values reaching 473.256 ± 5.54, 536.374 ± 2.87, 567.694 ± 4.22, and 601.911 ± 6.54 MPa for TRB‐3, TRB‐6, TRB‐9, and TRB‐12, respectively. The developed composites achieve relative densities greater than 97%, indicating promising applications in the aerospace, automotive, and marine industries.

Optimization of UV-Curable Polyurethane Acrylate Coatings with Hexagonal Boron Nitride (hBN) for Improved Mechanical and Adhesive Properties.

Polymer coatings are widely used in industries for protection, decoration, and specific applications, typically including volatile organic compounds (VOCs) to achieve low viscosity. The growing environmental concerns and the anticipated limits on fossil feedstock have driven the coating industry towards eco-friendly alternatives, with UV-curing technology emerging as a promising solution due to its energy efficiency, low-temperature operation, reduced VOC emissions, and high curing speed. Polyurethane acrylates (PUAs) are critical in UV-curable formulations, offering excellent flexibility, impact strength, optical, and adhesion properties. However, UV-cured PUA coatings face limitations in thermal stability and tensile strength, which can be addressed by incorporating fillers. This study investigates the effects of multi-functionalized hexagonal boron nitride (hBN) nanoparticles on the mechanical, thermal, optical, and adhesion properties of UV-cured PUA films and coatings for pre-coated metals. The results demonstrated that incorporating hBN nanoparticles enhanced the mechanical and thermal properties of the nanocomposite films, with optimal performance observed at 0.5% hBN loading. Despite the improved properties, the FTIR spectra indicated that the low concentration of hBN did not produce significant changes, potentially due to the overshadowing signals from the difunctional polyurethane acrylate.

Novel approach to corrosion resistance and radiative cooling with biomimetic amorphous coatings

To address the application challenges of high-power-density electronic devices in harsh conditions, it is crucial to develop electric insulation materials that possess both corrosion resistance and excellent radiative cooling performance. In this study, inspired by the wrinkle morphology of the Camponotus ant with thermoregulation, a biomimetic amorphous coating composed of a hemispherical array was fabricated on aluminum alloy using plasma electrolytic oxidation (PEO) technology. This biomimetic microstructure is obtained by controlling the content of hexagonal boron nitride (h-BN) nanoparticles in the electrolyte, where the increase in current density at a later stage allows the transition of the porous coating to the hemispherical array. The effects of functional group vibration and rotation in combination with the hemispherical structure afford the biomimetic coating a high emissivity of 0.91 within the range of 3–14 μm, which reduces the LED temperature by 17.1 °C and achieves a cooling efficiency of 10.6 %. Meanwhile, with a resistivity of 5.15 × 1014 Ω∙cm and a dielectric strength of 29.9 V/μm, the coating can prevent current leakage, consequently improving the stability and reliability of electronic packaging materials. In addition, h-BN flakes in the biomimetic coating with almost defects free act as a protective barrier to enhance the corrosion resistance of the aluminum alloy. This approach offers a time-efficient and cost-effective route for the manufacture of multifunctional coatings with potential applications in electronic packaging.

HBN/PVDF‐HFP and BNNS/PVDF‐HFP nanocomposites as flexible and lightweight dielectric capacitors: High energy storage performance via electrically insulating nanoparticles

AbstractAs the energy demand continuously increases, polymer‐based materials have attracted much attention for energy storage systems as dielectric capacitors due to their higher power density and charge–discharge rate than lithium‐ion batteries and supercapacitors. However, it is necessary to increase the energy density of dielectric capacitors. In this context, poly(vinylidene fluoride‐co‐hexafluoropropylene), PVDF‐HFP, matrix nanocomposites are produced by solution casting method reinforced with hexagonal boron nitride (hBN) nanoparticles and silane‐modified boron nitride nanosheets ‐BNNSs‐ (BNNS‐VTS) up to 10 wt.% filler content. The effects of filler content and surface modification of hBN/BNNSs on PVDF‐HFP matrix nanocomposites' microstructure, phase evolution, crystalization behavior, dielectric properties, and energy storage performance are discussed. 4% hBN/PVDF‐HFP nanocomposite demonstrates 641 MV·m−1 of breakdown strength and 23.2 J·cm−3 of discharged energy density due to hexagonal boron nitride's excellent electrical insulating behavior. The achieved values are 3.0 and 10.5 times superior to the values of the neat thin film, respectively, and they are noteworthy among hBN‐ or BNNS‐reinforced PVDF‐based nanocomposites, even in multi‐layered structures. Furthermore, 4% hBN/PVDF‐HFP presents a giant charge–discharge energy efficiency (92%). It is thus demonstrated that hBN/PVDF‐HFP nanocomposites hold a great potential to be used in energy storage applications as flexible and lightweight dielectric capacitors.Highlights PVDF‐HFP matrix nanocomposites for electrical energy storage as flexible dielectric capacitors hBN NPs and silane‐modified BNNSs are reinforced into the matrix by 0–10 wt.%. The effects of filler content and surface modification of hBN/BNNSs are discussed. 4% hBN loading results in 23.2 J·cm−3 energy density and 92% efficiency at 641 MV·m−1 breakdown strength. Those metrics are relatively high in hBN‐ or BNNS‐reinforced PVDF‐based nanocomposites.

Preparation of BN Nanoparticle with High Sintering Activity and Its Formation Mechanism.

Hexagonal boron nitride (h-BN) nanoparticles have attracted increasing attention due to their unique structure and properties. However, it is difficult to synthesize h-BN nanoparticles with uniform spherical morphology due to their crystal characteristic. The morphology control by tuning their precursor synthesis is a promising and effective strategy to solve this problem. Especially, the treatment temperature of precursors plays an important role in the morphology and surface area of h-BN nanoparticles. Herein, h-BN nanoparticles with different morphologies were synthesized via regulating the treatment temperature of precursors. The result shows that treatment temperature will affect the microstructure and state of precursor and further influence the morphology of h-BN products. Benefiting from the unique structure, the h-BN obtained using 250 °C precursors shows higher specific surface area (61.1 m2 g-1) than that of 85 °C (36.5 m2 g-1) and 145 °C (27.9 m2 g-1). h-BN products obtained using 250 °C precursors show higher specific surface area than that of 85 °C and 145 °C. The optimal condition for obtaining high-quality spherical h-BN is the pretreatment temperature of 250 °C and sintering temperature of 1300 °C. Importantly, compared with commercial h-BN nanoparticles, the synthesized h-BN nanoparticles show more uniform structure and larger specific surface area, indicating that sintering activity will be greatly improved. Furthermore, the reaction pathway and formation mechanism of h-BN was revealed by DFT calculations. The result shows that the five stationary states and five transition states exist in the reaction pathway, and the energy barrier can be overcome at high temperatures to form a ring h-BN. In view of its simplicity and efficiency, this work is promising for designing and guiding the synthesis of h-BN nanoparticles with uniform morphology.

Effects of Hexagonal Boron Nitride and Mesoporous Silica Nanoparticles on the Morphology, Mechanical Properties and Antimicrobial Activity of Dental Composites

Hexagonal boron nitride (HBN), an artificial material with unique properties, is used in many industries. This article focuses on the extent to which hexagonal boron nitride and silica nanoparticles (MSN) affect the physicochemical and mechanical properties and antimicrobial activity of prepared dental composites. In this study, HBN, and MSN were used as additives in dental composites. 5% and 10% by weight of HBN are added to the structure of the composite materials. FTIR analysis were performed to determine the components of the produced boron nitride powders, hexagonal boron nitride-containing composites, and filling material applications. The structural and microstructural properties of dental composites have been extensively characterized using X-ray diffractometry (XRD). Surface morphology and distributions of nano boron nitride were determined by scanning electron microscopy (SEM)-EDS. In addition, the solubility of dental composites in water and their stability in water and chemical solution (Fenton) were determined by three repetitive experiments. Finally, the antimicrobial activity of dental composites was detected by using Minimum Inhibitory Concentration (MIC) measurement, as well as Minimum Fungicidal Concentration (MFC) method against yeast strain Saccharomyces cerevisiae, and Minimum Bactericidal Concentration (MBC) method against bacteria strains, Staphylococcus aureus and Escherichia coli. Since the HMP series have better antimicrobial activity than the HP series, they are more suitable for preventing dental caries and for long-term use of dental composites. In addition, when HMP and HP series added to the composite are compared, HMP-containing dental composites have better physicochemical and mechanical properties and therefore have a high potential for commercialization.

Improvement in Tribological Properties with Addition of Hexagonal Boron Nitride (h-BN) and Molybdenum Disulfide (MoS2) Nanoparticles in Aerospace Lubricants

In the aircraft mounted accessory gearbox and gas turbine engine gearbox, a significant rise in temperature of lubricant was consistently observed due to the high coefficient of friction (COF) between the moving parts. This phenomenon limits the speed and power transmission of the gearbox. To resolve this, the current study recommends adding specific nanoparticles (NP) as an additive to the military (MIL) grade lubricant to reduce frictional resistance between the gears. Surfactants were also added to hexagonal boron nitride (h-BN) and molybdenum disulfide (MoS2) nanolubricants (NL) to improve NP suspension. Tribological investigations were conducted with a four-ball tester, a shear stability tester, and a Reichert tester to examine the lubricants. During the four-ball test, the wear scar diameter (WSD) on the specimen decreased by 16.73% and 12.3% with h-BN and MoS2 NL, respectively, compared to the results obtained using the base lubricant (BL). In the shear stability test, h-BN NL demonstrated 93%, and MoS2 NL demonstrated 67% more shear stability than the BL, while the COF was reduced by 13% in both h-BN and MoS2 NLs during the Reichert test. These test results prove that h-BN and MoS2 NPs, when added to a MIL standard BL, can demonstrate improved tribological capabilities even at extreme operational conditions.

Assessment on thermophysical properties of nano enhanced heat transfer fluid with hexagonal boron nitride nanoparticles for thermal management of photovoltaic thermal (PVT) system

One of the most promising sources of energy to meet demand and reduce pollution from fossil fuels is solar energy. To maximize energy conversion, solar technology efficiency, whether it comes from thermal systems, photovoltaic panels, or a hybrid known as photovoltaic-thermal (PVT) systems is critical. This work looks into the formulation and thermophysical of hBN-water nanofluids, with an emphasis on how they might be used as coolants in PVT systems to improve electrical performance. After a meticulous preparation process, the nanofluids exhibited exceptional stability, confirmed through visual inspection and zeta potential evaluation. Zeta potential analysis revealed consistent values across different temperatures and volume concentrations. Density decreased with temperature, while viscosity increased with volume concentration but decreased with temperature. Thermal conductivity showed a consistent increase with volume concentration and temperature. Through optimization, the 0.5 vol% concentration was identified as optimal for the PVT system. Compared to no coolant and water-based coolant scenarios, hBN-water nanofluids effectively regulated cell temperatures between 40.25°C and 46.34°C, demonstrating superior thermal conductivity and heat transfer properties. Moreover, the nanofluid coolant enhanced the PVT system's electrical performance. Open circuit voltage remained consistent (19.67 V to 20.81 V), short circuit current and output power improved with higher irradiance levels, and electrical efficiency, thermal efficiency and overall efficiency reached 5.73–5.88 %, 54.15–62.73 % and 59.88–68.62 % respectively These findings underscore the potential of hBN-water nanofluids in enhancing thermal management and electrical performance in solar energy systems. By minimizing thermal losses and maximizing electrical output, nanofluid coolants offer promising avenues for optimizing the efficiency of renewable energy technologies.

Effect of hBN and SDS added vegetable based cutting fluid application on the performance of turning Ti6Al4V alloys: A Comparative analysis with Taguchi and ANN approaches

In this study, during the turning process of Ti6Al4V alloy, which is difficult to machine, nanofluid, whose base fluid is vegetable oil (sunflower oil), was applied to the cutting zone with the minimum quantity lubrication (MQL) technique. Nanofluids were prepared by adding hexagonal boron nitride (hBN) nanoparticles (65–75 nm) with different concentration ratios (0.5 and 1 %) and surfactant (Sodium dodecyl sulfate, SDS) into vegetable oil. Thermal conductivity coefficients and dynamic viscosities of the prepared nanofluids and pure sunflower oil were measured at four different temperatures. Additionally, the stability of the prepared nanofluids was observed for 15 months. In turning experiments, four different cutting speeds (50, 75, 100 and 125 m/min), four different feed rates (0.05, 0.10, 0.15 and 0.20 mm/rev) and four different cooling conditions (dry, PureMQL, 0.5 % NanoMQL and 1 % NanoMQL) were used. The effect of the change in these parameters on surface roughness (Ra), temperature in the cutting zone (T) and flank wear on the tools (Vb) was investigated experimentally and analytically. As a result of the research, the experimental results were evaluated using variance analysis, signal/noise (S/N) analysis and artificial neural networks (ANN) methods. As a result of the measurements and observations, it was determined that the nanofluid with 0.5 % concentration had the best stability. In the main experiments, the MQL condition using this nanofluid (0.5 % NanoMQL) exhibited the best machining performance. In the wear experiments, the lowest tool wear was detected under the 1 % NanoMQL condition. According to the ANOVA and S/N analysis results showed that Ra was most affected by the feed rate (95 %), T was most affected by the cooling condition (70 %), and Vb was most affected by the cutting speed (45 %). The prediction performances of ANN and Taguchi approaches were examined and the prediction success of these approaches was more than 98.5 % and 80.8 %, respectively. Especially for Vb values that have very close data, more accurate predictions were made with the ANN approach compared to Taguchi.

Effects of temperature and concentration of nanoparticles on rheological behavior of hexagonal boron nitride/coconut oil nanofluid

In this work, a nano-lubricant composed of hexagonal boron nitride (hBN) nanoparticles suspended in pure coconut oil was developed using a two-step method that involved ultrasonic assistance. The synthesis was carried out at varying solid volume concentrations, ranging from 0.2% to 1.2%. X-ray diffraction and Transmission electron microscope techniques were utilized to conduct investigations into the structure and morphology of nanoparticles. These examinations reveal that the nanoparticles exhibit a hexagonal arrangement, with an average diameter measuring 40 nm. The viscosity of pure coconut oil/ hexagonal boron nitride (hBN) nanofluids was evaluated at temperatures ranging from 303 to 403 K. utilizing shear rates varying from 10 to 50 s−1. With the use of a rotational Anton Paar rheometer, the shear dynamic viscosity of the nanofluids was determined. The study focused on examining how the viscosity of pure coconut oil/ hexagonal boron nitride (hBN) nanofluids is influenced by variations in solid volume concentration and temperature. The results revealed that as the temperature increased, the viscosity of the nanofluids decreased. Conversely, when the quantity of nanoparticles was raised in the base fluid, the nanofluids demonstrated an increase in viscosity values. This study found that at a shear rate of 10 s−1, the nanofluid with a 1.0% solid volume concentration exhibits a viscosity 58% higher at 303 K compared to 403 K. Additionally, it was observed that when the concentration of nanoparticles increased from 0% to 1%, and the shear rate decreased from 50 to 10 s−1, the viscosity of the nanofluid increased by 32% at 303 K temperature. Furthermore, this study shows a significant impact of hexagonal boron nitride (hBN) nanoparticles in pure coconut oil as the prepared nanofluids with different nanoparticle concentrations demonstrated a relative viscosity higher than one.

Negatively charged boron-vacancy defect in hexagonal boron nitride nanoparticles

Fluorescent defects in two-dimensional (2D) hexagonal boron nitride (hBN) crystals have attracted a great potential in quantum information and sensing technologies. In particular, the negatively charged boron vacancy (VB−) center has shown spin-dependent fluorescence in 2D flakes or large hBN crystals, which can be manipulated at room temperature, enhancing the application scope of hBN in quantum technologies. In this work, we demonstrate the generation of this interesting spin defect in small hBN nanoparticles (NPs) with a size range of 10–50 nm. The obtained optical properties of the VB− showed a photostable photoluminescence peaked at 820 nm with a spin-lattice relaxation time (T1) of 17 μs and optically detected magneto resonance (ODMR) contrast of 10%. Achieving long T1 time and high ODMR contrast is crucial for effective quantum sensing using small hBN nanocrystals. The reported spin-optical properties of the generated VB− spin defect in hBN NPs are comparable to those created in bulk/flake hBN crystals. These results open the door for optimizing such spin-dependent defects in small hBN NPs for promising applications, especially in quantum sensing and biology.

Thermal properties analysis and thermal cycling of HITEC molten salt with h-BN nanoparticles for CSP thermal energy storage applications.

Molten salts are the operational fluid for most concentrated solar power (CSP) systems, which has attracted more attention among the scientific community due to the augmentation of their properties with the doping of nanoparticles. Hexagonal boron nitride (h-BN) nanoparticles were dispersed in HITEC molten salt to create a novel nanofluid and evaluate the h-BN nanoparticles' influence on HITEC thermophysical properties. The influence of nanoparticle concentration (0.1, 0.5, and 1wt.%) of h-BN and HITEC was studied in this research. HITEC and nano-enhanced HITEC molten salt (NEHMS) were characterized using energy-dispersive X-ray spectroscopy (EDX), field emission scanning electron microscopy (FESEM), and Fourier transform infrared spectroscopy (FT-IR). Specific heat capacity, latent heat, and melting temperature were assessed using differential scanning calorimetry (DSC). The maximum working temperature was evaluated with thermogravimetric analysis (TGA). The ideal nanoparticle concentration is 0.1 wt.% h-BN, which results in a 27% increase in heat capacity, a 72% increase in latent heat, and a 7% enhancement in thermal stability. The thermal cycling stability test proved the stability of the enhanced thermophysical properties. The material characterization revealed that the samples with improved thermophysical properties have a homogeneous dispersion of nanoparticles with minor nanoparticle agglomeration. The system advisor model (SAM) simulation comparison of the optimum sample with solar salt and HITEC salt revealed that using the optimum sample increases CSP plant efficiency by 0.4% and reduces power costs by 0.13¢/kWh.

Enhancement of Flexural Strength by Slip Casting Cordierite Ceramics with h-BN Nanoparticles

In this study, we enhanced the flexural strength of cordierite ceramics by incorporating h-BN (hexagonal boron nitride) nanoparticles, facilitated by the slip casting process. Initially, commercial cordierite powder with an average particle size of 10 mm underwent a ball-milling process to reduce the size to 2.5 mm and simultaneously achieve a narrower particle size distribution. The resulting slurry, composed of 67% solid content, exhibited improved stability during the slip casting process for both pristine cordierite and the mixture containing 1 – 2 wt% h-BN nanoparticles. After sintering, the bulk material containing 2wt% h-BN nanoparticles demonstrated a remarkable flexural strength of 174.8 MPa, a significant improvement compared to the initial 119.5 MPa obtained without the addition of h-BN. It is worth noting that the introduction of h-BN nanoparticles did not induce substantial changes in dielectric constant and thermal conductivity, indicating that the desired mechanical enhancement did not compromise other crucial material properties. This research demonstrates a successful approach to concurrently optimize the flexural strength, dielectric constants, and thermal conductivity of cordierite ceramics. This breakthrough opens up new avenues for advanced applications in a wide range of fields, from electronics to aerospace, where high-strength, thermally stable materials are in demand.

Effects of using fireproof thermal management systems on the lifespan of battery cells

The current need, from the point of view of increasing the sustainability of electric vehicles (more and more present in the car market), makes the research in the field to be focused on the analysis of the factors that can lead to an increase electric vehicle batteries' lifespan. Since this is directly related to the temperatures reached during operation and the thermal gradients inside the battery packs, this paper presents the analysis of the cells' lifespan through artificial intelligence methods and techniques, evaluating the influence of the constructive and functional characteristics of two air-based hybrid thermal management systems (CHA - composite material + heat pipe + forced air convection and CTA - composite material + thermoelectric cooler + forced air convection). The construction of the thermal management system is a special and innovative one, being a composite material (epoxy flame-retardant resin and 2 wt% hexagonal boron nitride nanoparticles) chosen as the primary thermal energy dissipation element. The research was carried out experimentally on individual cells and on a battery module (consisting of 12 cylindrical Li-ion 18650 cells), the battery module being discharged at a rate of 3C with the temperatures recorded from 15 locations inside the battery module, which allows assessing the local and global influence of the thermal management systems. Predictions on the lifetime of the cells in the battery module were made using a convolutional neural network and showed that by using the proposed fireproof thermal management systems, the cells’ lifespan increases by 26.9 … 154.4% (depending on the implemented thermal management system and the location of the cell in the battery module).

Preparation of Ti4O7/h‐BN self‐supported ceramic photoelectrode and its photoelectrocatalytic performance for water purification

AbstractThe construction of high‐efficiency self‐supported ceramic photoelectrode based on ideal semiconductor materials is essential for achieving effective degradation of pollutants by photoelectrocatalysis (PEC) technology. Herein, a Ti4O7/h‐BN composite ceramic photoelectrode with a unique microstructure was fabricated by a step‐by‐step calcination process and used in PEC water pollution remediation. The PEC activity of Ti4O7 ceramic photoelectrode could be enhanced by introducing hexagonal boron nitride (h‐BN) nanoparticles on the surface. The most optimized Ti4O7/h‐BN photoelectrode exhibited the decolorization rate of active brilliant blue KN‐R at about 97.79% in 30 min. The PEC activities could remain stable during five degradation cycles. The excellent photoelectrocatalytic performance of Ti4O7/h‐BN ceramic photoelectrode could be attributed to the low Tafel slope, low charge transfer resistance, large electrochemical active area, and excellent photo‐generated carrier separation efficiency. A type‐II heterojunction was formed between the Ti4O7 and h‐BN, which caused more effective carrier separation and enhanced the generation of dominant active species •O2− and h+. This work provided a mature synthesis strategy of Ti4O7/h‐BN self‐supported ceramic photoelectrodes with excellent practical application prospects to achieve superior PEC performance for water purification.

Investigating Friction and Antiwear Characteristics of Organic and Synthetic Oils Using h-BN Nanoparticle Additives: A Tribological Study

Friction and wear are two major elements that influence the life of a variety of equipment. According to estimates, as much as 30% of the energy used is dissipated as friction. However, this figure can be reduced by developing materials that enhance surfaces and apply lubricants appropriately. This study aims to analyze the impact of hexagonal boron nitride (h-BN) nanoparticles on the rheological and antiwear characteristics of four distinct oil varieties, namely Society of Automotive Engineers SAE-20W50, soybean, Polyalphaolefin PAO-4, and olive oils. The results of the tribological tests demonstrated a noteworthy enhancement in antiwear characteristics with the addition of 0.2 wt.% of h-BN nanolubricant. Among all nanolubricants, the maximum reduction in coefficient of friction (COF) and wear scar diameter was observed at 0.2 wt.% of h-BN in SAE-20W50 oil. Compared to the base oils, the wear scar diameter decreased by 17.93%, 8.80%, 22.65%, and 24.04% for (soybean oil and 0.2 wt.% of h-BN), (SAE20W50 and 0.2 wt.% of h-BN), (PAO4 and 0.2 wt.% of h-BN), and (olive oil and 0.2 wt.% of h-BN), respectively. Rheological test results indicated that with the addition of h-BN nanoparticles, the viscosity of the base oils significantly increased. The maximum viscosity was observed at 40 °C for SAE20W50 base nanolubricants, according to the rheological measurements.

Regulation and prediction of the dielectric constant and interfacial binding energy of surface modified hexagonal boron nitride/polyphenylene oxide@cyanate ester resin

AbstractParticulate‐filled materials with superior mechanical properties and wave permeability have received extensive research attention in the military industry. To elucidate the role of reinforcement in polymers, γ‐Aminopropyltriethoxysilane (APTES) is used to modify hexagonal boron nitride (h‐BN) nanoparticles, which are then filled into polyphenylene oxide@bisphenol A dicyanate ester composite, exhibiting a 1.46‐fold increase in flexural strength and a dielectric constant of 2.66 at 12 GHz. Finite element analysis is employed to design composite material models, successfully predicting the dielectric properties of composites at different frequencies and reinforcement filling levels. The change in the interface energy induced by the silane coupling agent is quantitatively calculated by molecular dynamics simulation, demonstrating that the modified nanoparticles are conducive to improving the flexural strength. Overall, the predicted dielectric and mechanical properties of composites can be utilized to screen for composites that possess excellent dielectric and mechanical properties, thereby greatly improving efficiency.Highlights A hexagonal boron nitride/polyphenylene oxide@cyanate ester is prepared. Finite element analysis is employed to predict the dielectric properties. The interface energy is calculated by molecular dynamics simulation. The resin has superior mechanical and dielectric properties.

4D printing of shape memory polymer nanocomposites for enhanced performances and tunable response behavior

The emergence of four-dimensional (4D) printing introduces a novel approach to the design and manufacturing of high-performance multifunctional shape memory polymers (SMPs). Herein, two types of nanomaterials were blended or embedded into SMPs matrix to enable 4D printing of shape memory polymer composites (SMPCs) via photocuring. The incorporation of hexagonal boron nitride (HBN) nanoparticles enhanced the thermal stability and mechanical properties of SMPs, and accelerated their thermally responsive shape recovery speed. HBN nanoparticles also significantly improved the performance stability of SMPs, even after undergoing multiple shape memory cycles. Electrically responsive shape memory behavior in SMPCs was achieved by embedding a spray-coated polyaniline: polystyrene sulfonate /graphene (PANI: PSS/GR) electrothermal layer (ETL). The applied voltage, ETL resistance, HBN blend content, and sample thickness had a significant regulation effect on electrically responsive shape recovery behavior and shape recovery force. PANI: PSS improved adhesion between ETL and SMPCs matrix, filled the gaps between graphene platelets, which resulted in rapid, uniform, and stable heating upon energization. The presented electrically responsive gripper was capable of grasping objects of various shapes and sizes. This strategy broadens the potential applications of 4D printed SMPCs in challenging environments while propelling the advancement of 4D printing.

Analyzing the thermal potential of binary 2D (h-BN/Gr) nanoparticles enhanced lauric acid phase change material for photovoltaic thermal system application

Thermal energy storage as latent heat is an effective strategy to preserve the excessive energy available. In this aspect, fatty acid phase change materials (PCMs) are promising materials since they have a high latent heat, nontoxic, and little sub-cooling. However, their inherently low thermal conductivity severely restricts their applicability. Herein, hexagonal boron nitride (h-BN) and graphene (Gr) binary nanoparticles (NPs) are taken as nano-additives to enhance thermal conductivity of lauric acid (LA). The NPs added PCM known as nano-enhanced phase change material (NePCM) is prepared by two-step method for thermo-physical characterization. According to an optical performance investigation using ultraviolet-visible spectroscopy (UV–Vis); optimal composite LBG2% (LA with 3 % h-BN and 2 % Gr NPs) displayed 78 % reduction in transmissibility compared to base LA. Further, LBG2% composites exhibited elevated thermal conductivity of LA by 97 %. Additionally, differential scanning calorimeter (DSC) observed a slight variation in latent heat and melting temperature. Latent heat for composite LBG2% found to be as 176 Jg−1 with a reduction equal to NPs weight% as compared to base LA. Moreover, the preferred composite LBG2% displays chemical stability and thermal reliability after 500 heating/cooling cycles. The addition of LBG2% NePCM to a photovoltaic thermal system increased electrical and thermal efficiency to 9.41 % and 69 %, respectively, as compared to the photovoltaic thermal system alone, which was 7.1 % and 64 %. It can be concluded, the binary NPs enhanced composite LBG2% exhibited improved photoabsoprtion and thermal conductivity, along with thermal reliability and higher latent heat. The composite has significant application potential within the melting temperature range of 50 °C for employment in solar photovoltaic systems and other applications.