Functionalization Of Boron Nitride Nanotubes Research Articles

Low-Temperature Triazine Functionalization of Boron Nitride Nanotubes for Applications from Drug Delivery to Advanced Composites

Low-Temperature Triazine Functionalization of Boron Nitride Nanotubes for Applications from Drug Delivery to Advanced Composites

Noncovalently functionalized boron nitride nanotubes and polymer nanocomposites with water-soluble poly (amic acid) salt

In this study, polyamic acid salt-BNNTs (PAS-BNNTs) were prepared by noncovalently functionalizing water-soluble PAS with improved dispersion stability in organic solvents, and high compatibility with polyimide (PI) nanocomposites. We show that BNNTs functionalized with PAS have enhanced mechanical properties that are influenced by various loadings of PAS-BNNT/PI films through in situ polymerization. Compared with the pure PI film, the tensile strength and tensile modulus increased by about 20% and 37%, respectively. The proposed system also improved the coefficient of thermal expansion (CTE) from 52.6 to 45.7 ppm/oC. The enhanced mechanical properties of the PI nanocomposite were due to the interfacial bond strength enhanced by the reinforcing effect of PAS-BNNTs. Our study demonstrates the potential of PAS-BNNTs for preparing BNNT/PI nanocomposites with various structures.

Functionalized boron–nitride nanotubes: First-principles calculations

With the use of density functional theory (DFT) calculations, we study the effect of functionalizing the surface of a boron nitride nanotube (BNNT) with hydroxyl (-OH) and carboxyl (-COOH) organic groups at the N and B sites. The results indicate that the -OH radical remains adsorbed in the B site whereas it is detached from the surface when added to the N site. Contrarily, the -COOH group remains attached for both adsorption sites. Both functionalizations induced a magnetic moment, produced spin-polarized electronic bands, created flat impurity-like bands, decreased the band gaps, and modified the electron density of the nanotubes. All of these changes can be used to control and modify the interaction of BNNTs with other molecules of interest like drugs, heavy metals, and greenhouse gasses, among other substances.

Controlled ultrasonication for covalent functionalization of boron nitride nanotubes

Controlled ultrasonication for covalent functionalization of boron nitride nanotubes

Covalent functionalization of boron nitride nanotubes through photo‐initiated chemical vapour deposition

AbstractBoron nitride nanotubes (BNNTs) are analogous nanostructures to carbon nanotubes (CNTs), possessing similar properties such as Young's modulus and thermal conductivity, but superior resistance to oxidation and thermal stability. In addition, BNNTs are insulating materials, whereas CNTs are electrically conductive. They could be used as reinforcements in polymeric matrices as heat dissipators or as protective coatings in harsh environments. However, when incorporating them into polymers, one main drawback is their tendency to agglomerate. To improve their dispersion, covalent surface modification can be applied, with solvent‐free approaches being preferred. Herein, we used syngas photo‐initiated chemical vapour deposition (PICVD) to incorporate oxygen functionalities on the surface of BNNT. X‐ray photoelectron spectroscopy analysis showed a highly oxidized BNNT surface after treatment. In addition, a decrease in water contact angle and an increase in surface energy were observed for the treated material. These results open new possibilities to incorporate hydrophilic BNNTs surfaces into polar polymers or other matrices of interest.

Quantum chemical studies to functionalization of boron nitride nanotube (BNNT) as effective nanocarriers

Quantum chemical studies to functionalization of boron nitride nanotube (BNNT) as effective nanocarriers

Noncovalently Functionalized Boron Nitride Nanotubes and Polymer Nanocomposites with Water-Soluble Poly (Amic Acid) Salt

Noncovalently Functionalized Boron Nitride Nanotubes and Polymer Nanocomposites with Water-Soluble Poly (Amic Acid) Salt

Amino acid functionalized boron nitride nanotubes as an effective nanocarriers for Thiotepa anti-cancer drug delivery

In the current study, the targeted drug delivery performance of the cysteine amino acid functionalized carbon nitride nanotubes (f-C3NNTs) was investigated towards the Thiotepa (TPA) anti-cancer drug through density functional theory (DFT). Also, we carried out calculations on pristine C3NNTs for the sake of better comparison. The results were demonstrating the exothermic and spontaneous nature of the drug absorption onto the nanocarriers. We observed the strongest interactions in f-C3NNTs/TPA complexes. Based on the calculations, when the TPA molecule is adsorbed onto f-C3NNTs, the adsorption distance is shorter, and the adsorption ability and solubility are higher in comparison with its adsorptions onto pristine C3NNTs. All of these complexes are polar, demonstrating their solubility in the aqueous medium. According to quantum molecular descriptors, the reactivity of nano-carriers of f-C3NNTs is more compared to that of pristine C3NNT nano-carriers. Based on the thermodynamic analyses, the interactions between the TPA molecule and f-C3NNTs are exothermic and spontaneous. Therefore, f-C3NNTs can be considered a good candidate for the adsorption of the TPA molecule for drug delivery system in nano-medicine.

Microwave radiation-assisted covalent functionalization of boron nitride nanotubes and their grafting with cationic thermo and pH-sensitive hydrogel

Sensitive hydrogels target the delivery of chemotherapeutic drugs to tumor tissues as these polymeric nets respond to environmental changes caused by growing cancerous tissues. A major concern with hydrogels is low mechanical resistance, what could be mitigated by combining these polymers to mechanically resistant inorganic materials like nanotubes. Boron nitride nanotubes (BNNT) exhibit biocompatibility and high mechanical resistance but are unable to control the release of molecules based on the conditions of a given suspension medium. Grafting sensitive hydrogels to BNNT presents a way to gather features of both phases, creating a potential drug delivery system (DDS) capable of withstanding the shear stress of the bloodstream. In this study BNNT were obtained via chemical vapor deposition (CVD) and oxidized by strong acids before being covalently functionalized by microwave radiation-assisted grafting. Thermo and pH-sensitive Poly[(N-iPAAm)-co-(DEAEMA)] hydrogels were synthesized using free radical polymerization both isolated, creating a purely polymeric sample, and in the presence of functionalized BNNT, creating the BNNT-TEGDMA/Poly[(N-iPAAm)-co-(DEAEMA)] hybrid sample. The hybrid sample represents the first time that, to the best of our concern, BNNT have been coated with in situ synthesized cationic hydrogel. The samples were characterized using XRD, SEM, TEM–EELS, FTIR, XPS, TGA, DSC, and elemental analysis. The results indicate that BNNT were successfully synthesized, oxidized, and covalently functionalized. These results also show that hydrogels were obtained in the absence and in the presence of functionalized nanotubes and could form the dual-phase hybrid material, which was shown to be sensitive to temperature and pH variations.

A mini-review on dispersion and functionalization of boron nitride nanotubes

A mini-review on dispersion and functionalization of boron nitride nanotubes

Fabrication of Noncovalently Functionalized Boron Nitride Nanotubes with High Stability and Water-Redispersibility.

Boron nitride nanotubes (BNNTs) have attracted significant interest because of the remarkable difference in their physical properties compared with carbon nanotubes and their far-reaching potential applications, including electrical insulators; thermally conducting, catalytic, and piezoelectric materials; and neutron absorbers. Despite their unique physical properties, the bundling and insolubility of BNNTs in water because of its substantial van der Waals attraction and hydrophobicity, respectively, give rise to many limitations in practical applications. Here, we present a new way to produce a highly stable BNNT dispersion by the noncovalent functionalization of the BNNT surface in water. The noncovalently functionalized BNNTs (p-BNNTs) have been found to be highly stable in water for a long time (>1 year) and easily water-redispersible by mild vortex mixing for a few minutes even after freeze-drying at -45 °C. The p-BNNTs were cylindrically encapsulated with polymerizable surfactants (BNNT diameter = ca. 3 nm and surfactant thickness = 0.8 nm).

Adsorption of NO2, HCN, HCHO and CO on pristine and amine functionalized boron nitride nanotubes by self-consistent charge density functional tight-binding method

The adsorptions of toxic gases including NO2, HCN, HCHO and CO molecules on the pristine and amine functionalized (5,0) single-wall boron nitride nanotubes (BNNTs) are investigated based on self-consistent charge density functional tight-binding (SCC-DFTB) method. The calculated results indicate that the pristine (5,0) BNNT exhibits weak adsorption for the gas molecules. Based on the calculated adsorption energy, interaction distances and charge transfer, amine functionalization at a boron atom of the pristine (5,0) BNNT enhances the sensitivity of the pristine (5,0) BNNT toward the gas molecules. The electronic densities of state results reveal that new local states in the vicinity of Fermi level for adsorption between amine functionalized BNNT and the gas molecules significantly appear. This confirms the improved sensitivity of the pristine (5,0) BNNT functionalized with amine for adsorption of the toxic gases. This study is expected to provide a useful guidance on gas sensing application of pristine and amine functionalized BNNTs for detection of the toxic gases at room temperature.

Capacity enhancement of polylithiated functionalized boron nitride nanotubes: an efficient hydrogen storage medium.

By using first principles density functional theory simulations, we report detailed geometries, electronic structures and hydrogen (H2) storage properties of boron nitride nanotubes (BNNTs) doped with selective polylithiated molecules (CLi2). We find that unsaturated bonding of Li-1s states with BNNT significantly enhances the system stability and hinders the Li-Li clustering effect, which can be detrimental for reversible H2 storage. The H2 adsorption mechanism is explained on the basis of polarization caused by the cationic Li+ of CLi2 molecules bonded with BNNT. The incident H2 molecules are adsorbed with BNNT-nCLi2 through electrostatic and van der Waals interactions. We find that with a maximum of 5.0% of CLi2 coverage on BNNT, an H2 gravimetric density of up to 4.41 wt% can be achieved with adsorption energies in the range of -0.33 eV per H2, which is suitable for ambient condition H2 storage applications.

PH-Controlled fluorescence switching in water-dispersed polymer brushes grafted to modified boron nitride nanotubes for cellular imaging.

pH-Switchable, fluorescent, hybrid, water-dispersible nanomaterials based on boron nitride nanotubes (BNNTs) and grafted copolymer brushes (poly(acrylic acid-co-fluorescein acrylate) – P(AA-co-FA)) were successfully fabricated in a two-step process. The functionalization of BNNTs was confirmed by spectroscopic, gravimetric and imaging techniques. In contrast to “pure” BNNTs, P(AA-co-FA)-functionalized BNNTs demonstrate intense green fluorescence emission at 520 nm. Under neutral or alkaline pH values, P(AA-co-FA)-functionalized BNNTs are highly emissive in contrast to acidic pH conditions where the fluorescent intensity is absent or low. No increase in the absorption was observed when the suspension pH was increased from 7 to 10. The functionalized BNNTs are easily taken up by human normal prostate epithelium (PNT1A) and human prostate cancer cell lines (DU145) and are suitable for further evaluation in cellular imaging applications.

In-Flight Plasma Functionalization of Boron Nitride Nanotubes with Ammonia for Composite Applications

Surface functionalization is an essential step to successfully harness the properties of boron nitride nanotubes (BNNTs) in several applications. Currently available functionalization methods are p...

Boron nitride nanotubes reinforced polycarbonate nanocomposites

Surface functionalized boron nitride nanotubes (f-BNNTs) with hydroxyl (OH) and amino (NH2) groups are employed as a nanofiller to reinforce polycarbonate (PC), a resin that has widely been used where a combination of transparency and high energy absorption is required, such as in armor, automotive and display technologies. To improve the interfacial compatibility of BNNTs with the PC matrix, BNNTs are treated with bromine in water inducing BN bond cleavage and subsequent formation of OH and NH2 functional groups on BNNT-surfaces. Samples of 1, 2 and 4 wt% f-BNNT/PC nanocomposite are prepared in a mixture of chloroform and dimethylformamide (DMF). The resulting f-BNNT/PC nanocomposites are processed in two ways: thin film formation from the powder by using a hot-press and plaque formation through melt-mixing-extrusion and compression molding techniques, respectively. The thermal and mechanical properties of the f-BNNT/PC nanocomposites are evaluated and compared with those of neat PC. They exhibit about 4∼8 °C improvement in thermal stability and over 30 °C higher in anti-oxidation than those of the neat PC. The testing result reveals that the f-BNNT/PC nanocomposite at 1 wt% loading achieves 39% increase in tensile toughness relative to the neat PC. Young’s modulus has an improvement by 13% (1 wt%) and 31% (4 wt%), respectively, from the thin-film samples; while about 2% and 13% improvements are observed from the extruded coupons at the same f-BNNT loadings. The transparency of the thin films is shown to decrease with the increase of f-BNNT loading.

Surface Modification and Functionalization of Boron Nitride Nanotubes via Condensation with Saturated and Unsaturated Alcohols for High Performance Polymer Composites

Over the past decade, boron nitride nanotubes (BNNTs) have been researched extensively due to their desirable physical, thermal, and mechanical properties. However, a major challenge for BNNT utili...

A mini-review on dispersion and functionalization of boron nitride nanotubes

Boron nitride nanotubes (BNNTs) are of intense scientific interest due to their unrivaled physicochemical characteristics, extraordinary thermal, electronic, mechanical, optical properties, and prospective applications in various nanotechnologies. Therefore, they are particular candidates for the development of new materials potentially applied in abundant applications. However, obtaining homogenous composite materials requires a good dispersion of BNNTs, as well in solvents or in the matrix, which still has remained challenging. The preparation of effective dispersions of BNNTs presents a major impediment to the extension and utilization of BNNTs. BNNTs intrinsically tend to bundle and/or aggregate. The prevention of such behavior has been explored by testing various techniques to improve the dispersibility of BNNTs in a variety of solvents. There are mainly two approaches to obtain a good quality dispersion; chemical functionalization and physical interactions. The chemical functionalization technique has been found effective, but deteriorates the intrinsic properties of BNNTs through the introduction of defects on the wall. Physical blending approaches with the ultrasound and high-speed shearing have been proven capable of debundling BNNTs and stabilizing individual BNNTs while maintaining their integrity and intrinsic properties. Attention has been brought to the study of the dispersion of BNNTs in aqueous media and most attention is paid to molecular dynamics (MD) simulation techniques and other physical techniques, as well as to the use of various surfactants and polymers.

Enhanced Thermal Conductivity in Polymer Nanocomposites via Covalent Functionalization of Boron Nitride Nanotubes with Short Polyethylene Chains for Heat-Transfer Applications

Boron nitride, which possesses high thermal conductivity, is often incorporated into polymer matrixes for thermal management. The enhancement in the thermal conductivity depends on the filler shape...

DFT and MD investigations on the functionalized boron nitride nanotube as an effective drug delivery carrier for Carmustine anticancer drug

In the present work, we apply density functional theory (DFT) calculations to investigate the drug delivery performance of the boron nitride nanotube (BNNT) having hydroxyl functional groups (-OH) for Carmustine (BCNU) agent in the gas phase and water environment. Based on the DFT results, it is found that the interaction between BCNU molecule and functionalized boron nitride nanotube (f-BNNT) is weak; so that, the adsorption of the BCNU drug on the nanotube surface is typically physisorption. Based on the structural characteristics, the stability of the BCNU/f-BNNT complexes contributed to the formation of the intermolecular hydrogen bonds (HBs) between the BCNU drug and hydroxyl groups of BNNT which confirmed by Bader theory of atoms in molecules (QTAIM) results. Our theoretical results show that the structural properties of BCNU molecule doesn't significantly change upon adsorption of drug molecule on f-BNNT. Moreover, the natural bond orbital (NBO) analysis show in BCNU/f-BNNT complexes, the charge transfers from f-BNNT to Carmustine drug and the electronic properties of BCNU drug are not affected during the adsorption process on the nanotube surface. Finally, the effects of drug concentration and temperature on the adsorption mechanism of BCNU molecules are investigated by molecular dynamics (MD) simulation. Such results provide valuable information on the potential applications of functionalized boron nitride nanotubes in the fields of drug delivery within biological systems.