Large-Scale Fabrication of Boron Nitride Nanosheets and Their Utilization in Polymeric Composites with Improved Thermal and Mechanical Properties

Nanomaterials have emerged as an amazing class of materials that consists of a broad spectrum of examples with at least one dimension in the range of 1 to 100 nm. Exceptionally high surface areas can be achieved through the rational design of nanomaterials. Nanomaterials can be produced with outstanding magnetic, electrical, optical, mechanical, and catalytic properties that are substantially different from their bulk counterparts. The nanomaterial properties can be tuned as desired via precisely controlling the size, shape, synthesis conditions, and appropriate functionalization. This review discusses a brief history of nanomaterials and their use throughout history to trigger advances in nanotechnology development. In particular, we describe and define various terms relating to nanomaterials. Various nanomaterial synthesis methods, including top-down and bottom-up approaches, are discussed. The unique features of nanomaterials are highlighted throughout the review. This review describes advances in nanomaterials, specifically fullerenes, carbon nanotubes, graphene, carbon quantum dots, nanodiamonds, carbon nanohorns, nanoporous materials, core–shell nanoparticles, silicene, antimonene, MXenes, 2D MOF nanosheets, boron nitride nanosheets, layered double hydroxides, and metal-based nanomaterials. Finally, we conclude by discussing challenges and future perspectives relating to nanomaterials.

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Nanomaterials: a review of synthesis methods, properties, recent progress, and challenges

Thermally conductive but electrically insulating polymer composites are highly desirable for thermal management applications because of their wide range of utilization, ease of processing, and low cost. However, the traditional approaches to thermally conductive polymer composites usually suffer from the low thermal conductivity enhancement and/or the deterioration of electrical insulating property. In this study, using cellulose nanofiber-supported 3D interconnected boron nitride nanosheet (3D–C–BNNS) aerogels, a novel method for highly thermally conductive but electrically insulating epoxy nanocomposites is reported. The nanocomposites exhibit thermal conductivity enhancement of about 1400% at a low BNNS loading of 9.6 vol%. In addition, the epoxy nanocomposites are still highly insulating, having a volume electrical resistivity of 1015 Ω cm. The strong potential application for thermal management has been demonstrated by the surface temperature variations of the nanocomposites with time during heating and cooling.

Cellulose Nanofiber Supported 3D Interconnected BN Nanosheets for Epoxy Nanocomposites with Ultrahigh Thermal Management Capability

Inspired by rich physics and functionalities of graphenes, scientists have taken an intensive interest in two-dimensional (2D) crystals of h-BN (analogue of graphite, so-called "white" graphite). Recent calculations have predicted the exciting potentials of BN nanoribbons in spintronics due to tunable magnetic and electrical properties; however no experimental evidence has been provided since fabrication of such ribbons remains a challenge. Here, we show that few- and single-layered BN nanoribbons, mostly terminated with zigzag edges, can be produced under unwrapping multiwalled BN nanotubes through plasma etching. The interesting stepwise unwrapping and intermediate states were observed and analyzed. Opposed to insulating primal tubes, the nanoribbons become semiconducting due to doping-like conducting edge states and vacancy defects, as revealed by structural analyses and ab initio simulations. This study paves the way for BN nanoribbon production and usage as functional semiconductors with a wide range of applications in optoelectronics and spintronics.

"White graphenes": boron nitride nanoribbons via boron nitride nanotube unwrapping

Carbon nanotubes are promising materials for various applications. In recent years, progress in manufacturing and functionalizing carbon nanotubes has been made to achieve the control of bulk and surface properties including the wettability, acid–base properties, adsorption, electric conductivity and capacitance. In order to gain the optimal benefit of carbon nanotubes, comprehensive understanding on manufacturing and functionalizing carbon nanotubes ought to be systematically developed. This review summarizes methodologies of manufacturing carbon nanotubes via arc discharge, laser ablation and chemical vapor deposition and functionalizing carbon nanotubes through surface oxidation and activation, doping of heteroatoms, halogenation, sulfonation, grafting, polymer coating, noncovalent functionalization and nanoparticle attachment. The characterization techniques detecting the bulk nature and surface properties as well as the effects of various functionalization approaches on modifying the surface properties for specific applications in catalysis including heterogeneous catalysis, photocatalysis, photoelectrocatalysis and electrocatalysis are highlighted.

Carbon nanotube catalysts: recent advances in synthesis, characterization and applications.

http://www.rsc.org/suppdata/c5/cc/c5cc04077a/c5cc04077a1.pdf

A high-yield ionic liquid-promoted synthesis of boron nitride nanosheets by direct exfoliation

Material recycling technology for automotive tire rubber waste was developed by the continuous devulcanization method. The deodorization during the recycling process has become possible by the newly developed method. The devulcanized rubber obtained by these methods from tire rubber waste, generated from both the manufacturing products and scrap tires, shows excellent mechanical properties applicable to the new tire rubber compounds in engineering practice. Furthermore, it was confirmed by actual road tests that a test truck tire containing 10 wt % of the devulcanized rubber in the tread might exhibit tread wear behavior almost equal to that for the standard type with the new rubber compound.

Recycling technology of tire rubber

Carbon nanotubes (CNTs), owing to their extremely high thermal conductivity (∼3000 W m−1 K−1), have recently attracted attention as notable nanofiller candidates to improve the thermal conductivity of polymers. However, CNTs cannot practically be used for highly electrically insulating polymers because even a few CNTs impart a high electrical conductivity to the polymers. Here, we design and fabricate CNT/polymer composites having a novel morphology, which achieves both enhanced thermal conductivity and high electrical insulation. This morphology comprises a matrix polymer and a CNT-localizing domain polymer encapsulated by a shell-forming component, which contributes to the selective localization of the CNTs into the dispersed domains. Such a controlled morphology is formed by the self-organization of the CNTs and the constituent polymers. A tailor-made morphology of CNT/polymer composite in accordance with our proposed model represents a promising route to a wide variety of applications of CNTs in materials requiring high electrical insulation.

A novel morphological model for carbon nanotube/polymer composites having high thermal conductivity and electrical insulation

A new production method for polypropylene-clay nanocomposites has been successfully developed. This method did not require the pretreatment of the clay mineral with an organo-cation. In this method we focused our attention on the nature of the clay mineral, which was exfoliated in water. Water was injected into a complex of melted polypropylene and a clay mineral in a twin-screw extruder. By controlling the pressure of the water vapor. the exfoliation of the clay mineral was achieved in the twin-screw extruder. Compatibilizers were added to the mixture of the clay mineral and the polypropylene to prevent aggregation, and we successfully prepared a polypropylene nanocomposite. The silicate layers of the clay mineral in this polypropylene nanocomposite were exfoliated and dispersed uniformly in the polypropylene matrix. This new type of polypropylene nanocomposite had almost the same properties as a conventionally prepared polypropylene-clay nanocomposite.

Development of a new production method for a polypropylene‐clay nanocomposite

Epoxy resin compositions including an epoxy resin, a hardener and an additive containing a rust preventing film forming component are provided. The additive is lanolin and/or a lanolin derivative. Optionally, the composition also includes a secondary additive selected from organosilicon compounds, organoaluminum compounds, organotitantium compounds, organotin compounds, liquid rubber having functional groups at both ends of the molecule, petroleum lubricating oils or Japan wax. These epoxy resin compositions, when used as encapsulating materials, prevent moisture and impurities from invading the surface of the device.

Mitsumasa Matsushita

Papers

A high-yield ionic liquid-promoted synthesis of boron nitride nanosheets by direct exfoliation

Recycling technology of tire rubber

A novel morphological model for carbon nanotube/polymer composites having high thermal conductivity and electrical insulation

Development of a new production method for a polypropylene‐clay nanocomposite

Epoxy resin composition