Ultrasonication Exfoliation

In contrast to the dry exfoliation of graphite, exfoliation with the assistance of ultrasonication in a liquid phase has also been investigated using various solutions, including organic, aqueous, as well as ionic liquids. 

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Ultrasonic exfoliation of graphite oxide and subsequent chemical reduction has been used to prepare reduced graphene oxide (rGO) [17]. This is a viable method for... 

The photochemical reduction has also been applied for synthesis of graphene-metal NPs. In this case, graphene-metal NPs nanocomposites were prepared by the irradiant white light instead of the chemical reducing agent In one report noble metal salts adsorbed on ultrasonication exfoliated graphene flakes, which were functionalized with ionic surfactants, were reduced... 

This study detects the defect of the void and the exfoliation in the solid phase diffusion bonding interface of ductile cast iron and stainless steel with a nickel insert metal using ultrasonic testing method, and examine the influence of mutual interference of the reflectional wave both the defect and the interface. 

Exfoliation is also facilitated by mechanical methods such as the application of high-intensity ultrasound. High-intensity ultrasound is known to increase the rate of intercalation reactions. However, in recent studies on the exfoliation of the misfit layer compounds PbNb2S5 and SmNb2S5, some degree of dispersion was obtained by ultrasonic treatment in specific solvents such as ethanol and isopropanol. ° The solvents were not intercalated, but acted to stabilize the dispersions. The dispersions contained a substantial fraction of particles with fewer than 10 layers, but only a small fraction was exfoliated. Along with the ion exchange reaction under relatively severe conditions compared with other layered... 

Epoxy-modified Mesua ferrea L. seed oil-based polyurethane/clay nanocomposites at different loadings (1-5 wt%) have been studied as biocompatible biomaterials. The partially exfoliated nanocomposites were prepared by an ex situ solution technique under high mechanical shearing and adequate ultrasonication at room temperature. The nanocomposites exhibited enhanced mechanical properties such as tensile strength (twofold) and scratch hardness (five-fold), thermostability (to about 40°C), and an increase in the rate of biodegradation between five- and ten-fold. All the nanocomposites showed RBC haemolysis inhibition observed by anti-hemolytic assay carried out on the sterilised films. 

For exfoliation of SWNT, the reported method from the literature is followed [9]. In the first step 0.2 wt% SWNT is dispersed in deionised water containing 1% anionic surfactant. With the help of ultrasonication and UV-Vis spectroscopy, the optimum exfoliation of the SWNT is obtained. The final wt% of SWNT in organic nanocomposite is calculated based on tbe yield of PANI. The weight % of SW NT mentioned in this chapter is relative to the yield of PANI. 

The method used to disperse clay into the monomer is important as good dispersion in the monomer is vital for the final nanocomposite morphology. Although the surface modification of the clay is a critical aspect in determining the compatibility between the styrene and the clay, the method used to disperse the day is also important, and in most cases some form of mechanical stirring is used as a minimum. Other methods can improve the ability to exfoliate including ultrasonic [87, 101] and direct electric current [102]. 

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