Exfoliation Of Boron Nitride Nanosheets Research Articles

Highly Anti‐Corrosive Performance of Poly(Vinylidene Fluoride‐Hexafluoropropylene)/Boron Nitride Nanosheet/Polyimide Composite Coating

AbstractPolyimide (PI) is one of the most important engineering plastics, but its stability in aqueous environments is insufficient, which limits its anti‐corrosion efficiency. In this study, a novel P(VDF‐HFP)/SMT‐RS@BNNSs/PI composite coating is prepared by incorporating poly(vinylidene fluoride‐hexafluoropropylene) (P(VDF‐HFP)) and the exfoliated boron nitride nanosheets (BNNSs) which were highly co‐functionalized with two kinds of materials of the rosin and the soy‐maleic anhydride‐tannic acid adhesive molecules (SMT‐RS@BNNSs). The coatings are characterized in detail by using the XRD, FT‐IR, XPS, and SEM technologies. Electrochemical impedance spectroscopy (EIS) and polarization curve tests further evaluated the corrosion resistance of the coating. As results, the obtained P(VDF‐HFP)/SMT‐RS@BNNSs/PI coating with good adhesion (grade 1) to the low‐carbon steel plate displays a larger water contact angle of 93.10° compared to blank PI (75.5°) and SMT‐RS@BNNSs/PI (83.2°). The dispersed distribution and interaction of SMT‐RS@BNNSs can effectively reduce the phase separation between P(VDF‐HFP) and PI. Even after soaking in electrolyte for 15 days, the impedance modulus, corrosion current, and corrosion voltage of the P(VDF‐HFP)/SMT‐RS@BNNSs/PI coating are 1.568 × 1010 Ω cm2, 4.612 × 10−12 A cm−2, and 0.325 V, respectively. These properties are superior to those of the PI and SMT‐RS@BNNSs/PI coatings. It is believed that the excellent anti‐corrosive performance of this PI‐based composite will broaden the application fields of PI materials.

Exfoliation of boron nitride nanosheets by liquid phase method based on deep eutectic solvents and their thermal management application

AbstractBoron nitride had emerged as an innovative thermally conductive filler, garnering increasing attention from researchers. However, there was a need to create new methods for efficiently producing functionalized boron nitride nanosheets with enhanced thermal conductivity and dispersion. In this study, a novel approach was introduced to utilize deep eutectic solvents as additives to facilitate the exfoliation of boron nitride nanosheets. This method offered significant advantages in terms of cost‐effectiveness (low additives level) and high yield (about 60%). Furthermore, the resulting epoxy resin composite material exhibited outstanding thermal conductivity and thermal management properties. The thermal conductivity of EP/d‐BNNS composites reached 1.02 W/mK at 20 wt% d‐BNNS loading. Additionally, the composite material demonstrated good thermal stability and low dielectric properties. This work demonstrated that this proposed approach represents an effective means for the scalable production of boron nitride nanosheets.Highlights The boron nitride nanosheets were obtained by deep eutectic solvents (DES) ball milling method. The exfoliated boron nitride exhibits superior dispersion stability. The thermal conductivity of EP composites is significantly improved.

High-flux polyamide nanofiltration membranes tuning by polydopamine-modified boron nitride nanosheets: Accelerating Mg2+/Li+ separation

As a promising technology for lithium extraction from salt lakes, nanofiltration membranes still face challenges in balancing between permeability and selectivity. In this paper, highly dispersed functionalized boron nitride nanosheets (BNNSs-NH2) were prepared by modifying exfoliated boron nitride nanosheets (BNNSs) with polydopamine, which were incorporated into a polyamide (PA) layer by aqueous phase conditioning to prepare positively charged polyamide nanofiltration membranes. Scanning electron microscopy (SEM) showed that the PDA nanoclusters on the surface of the BNNSs can disrupt the regular stacking parallel to the membrane surface. Energy spectrum (EDS) of SEM and X-ray photoelectron spectroscopy (XPS) etching further revealed that BNNSs-NH2 were dispersed within PA layer, creating transmembrane channels for molecular diffusion. The results showed a pure water permeance of 8.55 ± 0.24 L/m2 h bar, indicating that the stabilized intercalation of BNNSs-NH2 in the PA layer synergistically improved the water permeability. Meanwhile, the retention rate of MgCl2 remained at 94 %, which was attributed to the enhanced compatibility between BNNSs-NH2 and polyamide matrix by the polydopamine coating (PDA) on the surface, as well as the Dornan effect repulsion by the enhanced positive charge on the membrane surface. After the three-stage nanofiltration of membrane, the Mg2+/Li+ ratio decreased from 50 to 0.12. Overall, this method balances permeability and selectivity by adjusting pore size and positive charge, potentially offering new ideas and insights for the preparation and development of nanofiltration membranes for Mg2+/Li+ separation.

Ultrasound‐assisted liquid phase exfoliation of boron nitride nanosheets as fillers for polyacrylate pressure‐sensitive adhesives with enhanced thermal conductivity

AbstractHexagonal boron nitride (h‐BN) is widely used as a filler to improve the thermal conductivity of polymers due to the high thermal conductivity, electrical insulation, and chemical stability. However, the small lateral‐size and poor compatibility limit h‐BN's performances and applications in thermal management. Here, boron nitride nanosheets (BNNSs) were prepared by liquid‐phase ultrasonic exfoliation using isopropanol (IPA) as solvent. Specifically, the BNNSs obtained by ultrasonication for 8 h with an initial concentration of h‐BN of 8 mg/mL have the best exfoliation effect and a high yield of 19.8%, showing a large lateral‐size of 1–2 μm and an ultra‐thin thickness. Then, the resulting BNNSs can be modified by grafting silane coupling agent of KH560 (m‐BNNSs), their micromorphology and chemical composition are characterized by various microscopies and spectrometers. Subsequently, polyacrylate pressure‐sensitive adhesives (PSAs) composites are prepared using m‐BNNSs as a thermally conductive filler by UV bulk polymerization, their thermal conductivity can be greatly improved by 250% compared with that of pure PSAs. For comparison, the thermal conductivity of m‐BNNSs/PSAs composites with filler content of 25 wt% is as high as 0.4382 W/(m K), which is 1.6 times higher than that of h‐BN/PSAs composites. In addition, the incorporation of BNNSs will improve the thermal stability, hardness, and 180° peeling force of the PSAs composites, which will stimulate the practical application of PSAs materials.

Enhanced tough recyclable hemiaminal dynamic covalent network with boron nitride composites material with high thermal conductivity at low filler content

The demand for thermal interface materials (TIMs) with outstanding heat dissipation capability is increasing due to the advancements of multifunctional, miniaturized and well-integrated electronic devices. Simultaneously, as the accumulation of e-waste continues to grow, the recyclability of TIMs has emerged as a pressing concern. Herein, we introduce a novel approach that combines flow casting and hot pressing to create a tough recyclable hemiaminal dynamic covalent network with boron nitride composites film, which shows exceptional recyclability and high thermal conductivity. This approach was accomplished by combining hemiaminal dynamic covalent networks (HDCNs) with ionic liquid crystal exfoliated boron nitride nanosheets (ILC(Cl)-BNNS) via in situ polymerization. The obtained HDCN/BNNS composites film can enjoy a remarkable in-plane thermal conductivity of 2.72 Wm−1K−1 under a BNNS loading of 9.00 wt%, thus achieving an impressive ≈1195% in thermal conductivity enhancement. Furthermore, the HDCN/BNNS composite film enables the recycling of the composites under mild conditions, resulting in the facile recovery of BNNS with nearly pristine morphology and an impressive yield of 72.50%. This work presents a novel approach for the design of recyclable and high-performance TIMs, offering promising prospects for future applications.

Highly Exfoliated Boron Nitride Nanosheets via Carboxyl Nanocellulose for Thermally Conductive Nanocomposite Films

Highly Exfoliated Boron Nitride Nanosheets via Carboxyl Nanocellulose for Thermally Conductive Nanocomposite Films

Enhanced anti-corrosive capability of waterborne epoxy coating by ATT exfoliated boron nitride nanosheets composite fillers

In this work, 2-amino-5 mercapto-1, 3, 4-thiadiazole/boron nitride nanosheets (ATT/BNNS) nanofillers were prepared via using ATT as intercalating agent to exfoliate BNNS by a liquid-phase assisted ultrasound method. The FTIR and the XPS consequences testify that the corrosion inhibitor ATT is successfully grafted onto BNNS. TEM results indicate that BNNS is adequately exfoliated by ATT and the agglomeration phenomenon is alleviated. BNNS, ATT and ATT/BNNS nanofillers were processed into the waterborne epoxy (WEP) respectively, and WEP composite coatings were then fabricated by a spraying method on the copper electrode. The EIS measurements demonstrate that WEP ATT/BNNS coating displays the best protective performance in combination with optical morphology observation under saline immersion, compared with other three coatings. It is mainly attributed to the combined action of active protection from ATT inhibitor and physical barrier from BNNS. The two-dimensional BNNS nanofiller dispersed in the WEP coating plays the role of physical barrier, forms a “labyrinth effect”, extends the invasion way of corrosive media, thus enhancing the physical barrier effect in the composite coating. Furthermore, ATT inhibitor can also diffuse through the coating to the copper substrate and build a safety shield to hold back further corrosion. Importantly, after 40 days immersion in 3.5 wt% NaCl solution, the value of impedance module at 0.01 Hz of WEP ATT/BNNS coating is about 2 orders of magnitude larger than that of pure WEP coating, revealing superior long-term anticorrosion performance.

Improving thermal/electrical properties of silicone rubber nanocomposite using exfoliated boron nitride nano sheets made by an effective/novel exfoliating agent

In this work, boron nitride nano sheets (BNNSs) were prepared by exfoliation of h-BNs using mono ethylene glycol (MEG) as a novel exfoliating agent. For comparison, isopropyl alcohol (IPA)/water mixture was also used for exfoliation of h-BNs. It was found that using MEG caused preparing nano layers with higher yield and lower thickness compared to the IPA/water mixture. Thereafter, silicon rubber nanocomposites contained 3 and 5 wt% of pure and exfoliated BNNSs were prepared and evaluated for thermal and electrical performances. It was found that h-BNs and exfoliated-BNs drastically enhanced thermal conduction of SR. The silicon rubber contained 5 wt% of the h-BN and exfoliated-BNs illustrated around 20 times higher thermal conductivities compared to pure SR. Exfoliation of h-BNs had negligible effect on improvement of thermal properties, however, it caused 5.7 and 2.3 times enhancement in the electrical volume resistivity compared to the pristine SR and pure h-BN containing nanocomposite, respectively. Both of the BNNSs caused improvement in the heat dissipation performances of SR matrix, however, the exfoliated one with MEG showed better performances. Based on the results, it was claimed that mono ethylene glycol could improve exfoliation of h-BNs and enhance the performances of silicon rubber.

Hierarchical engineering of boron nitride nanosheets to reveal ignition mode of action of epoxy

AbstractIn the manuscript, the coupled parameters to influence ignition mode of charring epoxy thermoset (EP) were systematically revealed by comparative experiments and simulation. Aiming to incorporating physical variables of heat conductivity (k), specific heat capacity (c) and chemical variable of thermal‐oxidation degradation, thermally exfoliated boron nitride nanosheets were hierarchically engineered via bioinspired manipulation. Ignition time (tig) was studied in cone calorimeter test, accompanied by the in situ temperature detection and finite‐element temperature simulation. The comparative study disclosed that the physical parameters (k and c) exerted a dominant effect at the heating stage. The thermal‐oxidation degradation took effect at the determination of composition and concentration of volatiles (pertaining to ignition temperature). The pyrolyzed depth served as the bridge to connect physical and chemical aspects. The study revealed the dominant role of physical parameters in determining tig compared with chemical parameters. The concentration of volatiles was more critical than their composition. The multi‐scale structure and property relationship was established. Additionally, the changed oxygen atmospheres exerted a significant impact on piloted ignition via tailoring chemical factor. In perspective, the work will reveal a more clear understanding and modulation of ignition safety via a rational nanoscale strategy toward thermosetting polymers.

Highly thermally conductive polymer-based composites with 3D exfoliated BNNS/functionalized SiC networks prepared by rapid solidification and hot pressing

High thermal conductivity polymer-based packaging materials can achieve effective heat diffusion, which is of great significance for the performance and longevity of electronic devices. Exfoliated boron nitride nanosheets (s-BNNS) containing smaller particle sizes, fewer layers, and more hydroxyl groups were prepared by ball milling and strong ultrasonic treatment in this work. The functionalized SiC (m-SiC) was obtained by ternary blend organic silanol modification, which promoted the compatibility between fillers and fillers, as well as fillers and matrix. By a facile strategy of rapid solidification and hot pressing, s-BNNS were distributed between and on the surface of m-SiC fillers to form m-SiC/s-BNNS/polyamide 6/polyethylene terephthalate (PA6/PET) composite films with 3D thermally conductive networks. The thermal conductivity of m-SiC/s-BNNS/PA6/PET composite reached a superior 6.98 W/(m·K) at a filler loading 85 wt%, which was 124.67% higher than that of SiC/PA6/PET composite without 3D thermal network formation. More interestingly, reverse non-equilibrium molecular dynamics (RNEMD) simulations show that the hybrid SiC/BNNS filler greatly reduces the porosity within the composite compared to only one kind of filler, which in turn improves the composite's thermal conductivity.

Preparation of boron nitride nanosheets by glucose-assisted ultrasonic cavitation exfoliation.

Boron nitride nanosheets (BNNSs) have been widely used in many fields due to their excellent properties. However, low preparation rates and difficulty in functionalization hinder their further development. This study proposes a novel glucose-assisted ultrasonic cavitation exfoliation (GAUCE) method with glucose as an auxiliary solution to prepare BNNSs. Results show that the method has a high preparation yield of 55.58%, which is higher than the average preparation yield of 33.86%. The mechanism of preparing BNNSs by GAUCE was also investigated. The exfoliation of BNNSs was achieved using the energy of ultrasonic cavitation bubble collapse, which will break the interlayer forces in h-BN. The grafting of hydroxyl groups decomposed by glucose on the edge and surface of BNNSs during cavitation prevented the re-aggregation of the nanosheets, thereby increasing the exfoliation yield of BNNSs. In addition, the contact angle of BNNSs prepared by GAUCE was reduced, and the hydrophilicity was greatly improved.

Remarkable enhancement in thermal performance of polypropylene carbonate by using exfoliated boron nitride nanosheets

Biodegradable polymers are expected to replace traditional petroleum-derived polymers to meet environmental needs. However, its poor heat resistance limits its wide use. Intensive efforts have been taken to enhance the heat resistance, but the results are less than satisfactory and involve complicated steps. In this work, a facile carboxymethylcellulose-boron nitride nanosheets (CMC-BNNS) are used to realize the heat resistance enhancement modification of biodegradable poly (propylene carbonate) (PPC). Sodium carboxymethylcellulose (CMC-Na) is used to exfoliate and functionalize hexagonal boron nitride (h-BN) for the first time. The obtained CMC-BNNS with a uniform size after differential centrifugation can be stably dispersed in water and organic solvents. Benefit from the surface multifunctional group and 2D splinting effect of CMC-BNNS, the resultant PPC/CMC-BNNS composites not only possess superior heat resistance, but also display better thermal conductivity and dynamic mechanical properties compared with PPC/BN composites. The glass transition temperature (Tg) of the of PPC/CMC-BNNS composites with 2.5 wt% CMC-BNNS loading content greatly increases to 39.19 °C from 27.39 °C of neat PPC. This work provides a novel route for exfoliating 2D materials and heat resistance modification of biodegradable polymers.

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.

In-situ growth of amorphous carbon on sucrose-assisted exfoliated boron nitride nanosheets: Exceptional water dispersibility and lubrication performance

Hexagonal boron nitride (h-BN) is considered to highlight great potential in achieving low friction and wear due to high thermal conductivity, superb oxidation resistance and chemical stability. Herein, a sucrose-assisted ball milling method for exfoliating and functionalizing h-BN is proposed, and then amorphous carbon wrapped boron nitride nanosheets (aC@BNNSs) are obtained by hydrothermal carbonization. Tribological test results showed that after adding aC@BNNSs in water, the friction coefficient and wear track width were reduced to 0.09 and 65 µm, respectively. The excellent tribological properties are attributed to the transition from amorphous carbon to ordered graphite structure. Therefore, this study paves the way for green preparation of few-layer BNNSs, and aC@BNNSs shows great potential to become a promising lubricant additive.

Liquid phase exfoliated nanosheets as multifunctional fillers to semicrystalline polymers

Two-dimensional (2 D) materials have emerged as important part of high-performance polymer nanocomposites, thanks to their immaculate and tunable properties. Layered double hydroxides (LDHs), in particular, have received much attention in the polymer industry as multifunctional fillers for polyolefins and vinyl polymers. Highly exfoliated boron nitride nanosheets (BNNSs) have been a reliable partner for polyesters and polyamides, especially as thermal conductivity fillers. In this article, we have critically reviewed the latest developments in the field of polymer nanocomposites based on 2 D materials, with special emphasis on liquid phase exfoliated LDHs and BNNSs. Liquid phase exfoliation delivers few-layered or even monolayered nanosheets, and further structural modifications or surface functionalizations of these nanosheets result in better compatibility with the polymer matrix. Trace amounts of the exfoliated 2 D nanofillers can significantly alter the crystallization kinetics, mechanical properties, thermal stability, thermal conductivity and flame-retardant properties of polymers. Through this review, we aim to track down some of the important contributions in this area along with our own works, and this article is expected to fertilize considerable progress in this field.

Remarkable Enhancement in Thermal Performance of Polypropylene Carbonate by Using Exfoliated Boron Nitride Nanosheets

Remarkable Enhancement in Thermal Performance of Polypropylene Carbonate by Using Exfoliated Boron Nitride Nanosheets

Laminated Cellulose Hybrid Membranes with Triple Thermal Insulation Functions for Personal Thermal Management Application

Wearable textiles with multiple thermal insulation functions would play a significant role in preventing heat loss and improving personal thermoregulation properties. However, the precise control over the wearable materials with integrated insulation properties as well as the mechanical properties and antibacterial properties remains a challenge. Herein, the laminated cellulose hybrid membrane (LCHM) with triple thermal insulation functions was prepared by orderly vacuum filtration of cattail stick cellulose (CSC), nickel-silver core–shell nanowires (Ni@Ag-NWs), and exfoliated boron nitride nanosheets (BNNS) for personal thermal management application. Characterization results showed that the LCHM has a sandwich structure with an inner layer of Ni@Ag-NWs, middle layer of CSC and an outer layer of BNNS. The LCHM exhibited synergistic thermal management properties via infrared radiation insulation, electrical heating, and thermal insulation from the external environment. In this laminated system, the Ni@Ag-NW layer has a low infrared emissivity (10%) and higher conductivity (1.0 × 107 S/m), which can achieve dual thermal management by reducing human radiation and electric heating of the metal layer. Moreover, the introduction of BNNS into the cellulose membrane can play the role of thermal insulation from the external environment in spite of instinct insulation properties of cellulose materials. The cellulose fibers with extraordinary flexibility are self-tangled or tangled with other fibers to ensure the mechanical properties of the LCHM. In addition, the LCHM showed remarkable antibacterial activity against Escherichia coli bacteria. The desirable human thermal management properties of a hybrid membrane, which are comparable to the reported wearable materials, together with the advantages of functional integration, easy preparation, and controllable functional structures, make them excellent candidates for wearable applications.

Simultaneously environmental-friendly exfoliation of boron nitride nanosheets and graphene and the preparation of high thermal conductivity nano-mixture composite membranes

Hexagonal boron nitride nanosheets (h-BNNS) and graphene (G) are considered to be the representative materials in the two-dimensional (2D) materials community. h-BNNS and G are considered to exhibit high potential in thermal management materials for their prominent thermal conductivity. However, the conventional methods to synthesize h-BNNS and G are restricted by several problems (e.g., high energy consumption, environmental pollution and complex preparation methods). In the present study, a xylitol (C5H12O5)-assisted ball milling method was developed for scalable synthesis of a 2D material mixture of h-BNNS and graphene (BNNS@G). With this method, about 52% yield could be achieved. Moreover, the produced mixture was re-dispersed; it also exhibited high stability in water. The method proposed in this study is capable of effectively transferring green chemistry solutions to the preparation. Besides, a green solution was also proposed to apply the synthesized BNNS@G. The as-obtained BNNS@G was mixed with the cellulose nanofiber solution to form a series of G@BNNS/CNF membranes that exhibited high flexibility and ultrahigh thermal conductivity. Furthermore, 70 wt% BNNS@G membrane (3.4 W/mK) exhibited the in-plane thermal conductivity 300% higher than the membrane without BNNS@G. Thus, it is suggested that the synthesized membranes exhibit high potentials in the thermal management of portable mobile devices.

Crystallization and thermal conductivity of poly (vinylidene fluoride)/boron nitride nanosheets composites

ABSTRACT In this work, boron nitride (BN) and exfoliated boron nitride nanosheets (BNNs) were employed as thermal conductive fillers to improve the thermal conductivity of poly(vinylidene fluoride) (PVDF) composites. Results suggested that the thermal conductivity of PVDF increases significantly with an increase in loading content of functional fillers. When the mass ratio of fillers was more than 30 wt%, the heat conduction network was formed. BNNs were capable of forming denser heat conduction network as per the SEM observations. In this scenario, PVDF/BNNs composites demonstrated excellent thermal conductivity. For example, the thermal conductivity of PVDF/BNNs (60/40) was 0.82 W/mK, which was 2.4 times and 17% higher than that of neat PVDF and PVDF/BN (60/40) counterpart, respectively. The non-isothermal crystallization of corresponding composite was studied by Mo method. Combining with XRD results, both BN and BNNs acted as the nucleation agents but had no effect on crystal forms.

Evaluation of antibacterial and catalytic potential of copper-doped chemically exfoliated boron nitride nanosheets

Boron nitride (BN) nanosheets were prepared by chemical exfoliation method and incorporation of Cu as a dopant was achieved using hydrothermal route. Hexagonal phase of BN (h-BN) was detected using x-ray difractometer (XRD). Functional group analysis with fourier transform infrared spectroscope (FTIR) was employed to identify the chemicals used in the process, which was then further confirmed with energy dispersive x-ray spectroscopy (EDS) coupled with FESEM. Optical analysis undertaken with UV–vis. spectroscopy indicated absorption at UV region. Raman spectroscopy was used to acquire molecular fingerprints of BN molecules. Photoluminescence (PL) spectroscopy was carried out to study the exciton behaviour of samples in order to elucidate the electron migration and transfer rate. Field emission scanning electron microscope (FESEM) and high resolution transmission electron microscope (HRTEM) were employed to examine the morphology and structure of materials. The experimental results indicate that Cu-doped BN nanosheets possess excellent catalytic potential and superior antibacterial activity.