Effects of Modification Degrees on the Colloidal Stability of Amphiphilic Janus Graphene Oxide in Aqueous Solution with and without Electrolytes

Abstract

Colloidal stability of modified graphene oxide (GO) is fundamental for its practical applications. Meanwhile, most of the investigations mainly focused on the nanosheets modified by a certain amount of modifiers and neglected the effects of the modification degree, which could vary the physical and chemical properties of modified GO and significantly affect its stability in solution. To the best of our knowledge, this study initially investigated the impact of modification degrees on the colloidal stability of graphene-based amphiphilic Janus nanosheets (JGO) via both experimental and theoretical approaches. The prepared JGO, asymmetrically grafted by dodecylamine, exhibited a direct relation between the modification degree and nanosheet thickness, refractive index, electrostatic properties, hydrophobicity, and the ultimate colloidal stability. In addition, the ionic strength imposed distinctive influences on the aggregation behavior of JGO. Based on the comparison between experimental results and theoretical calculation, it was revealed that the JGO should be modeled as twodimensional (2D) nanosheets in pure water and be treated as 3D spherical particles in electrolyte solutions for the prediction with the extended Derjaguin−Landau−Verwey−Overbeek theory.

Performance Evaluation and Formation Mechanism of Viscoelastic Surfactant Fracturing Fluids with Moderate Interfacial Activity Enhanced by Janus-SiO2 Nanoparticles

“…The smaller CAs on wax-coated glasses than that on glasses for JANPs illustrate their amphiphilic structures patently, whose one side is more hydrophilic than the opposite side. 36 In addition, the gradually increased CAs of various NPs deposited on glass from HLNPs (∼0°) to JA12C (∼ 127°) further confirm the successful modification to HLNPs, which can also be indicated by the Pickering emulsion experiment (Figure S3).…”

A Meta-Analysis to Revisit the Property–Aggregation Relationships of Carbon Nanomaterials: Experimental Observations versus Predictions of the DLVO Theory

“…Since the methods used to characterize the hydrodynamic size and ζ-potential of nonspherical nanomaterials treated them as spherical nanoparticles that have the same average translational diffusion coefficients, we therefore used analytical expressions of interaction energy derived for spherical particles in the modeling. The use of sphere–sphere DLVO model for nonspherical nanomaterials has been demonstrated in previous individual studies and satisfactory results were reported. ,, …”

“…The varied experimental approach could weaken the validity of the comparison among studies. Rationale for criterion 2 is that the aggregation behavior of coated nanomaterials is largely determined by the properties of the surface coating rather than those of the “bare” nanomaterial. ,− …”

“…The use of sphere−sphere DLVO model for nonspherical nanomaterials has been demonstrated in previous individual studies and satisfactory results were reported. 12,26,43 Assuming that the thickness of the electrical double layer is much smaller than the particle size, the Derjaguin approximation was applied to obtain the electrical potential energy between two spherical particles in the a:b electrolyte 25…”

Ionic Liquid/Functionalized Graphene Oxide as a Nano Additive for Corrosion Protection and Lubrication

“…The morphologies of GO, Ch–Trp/GO, and Ch–Met/GO were observed by using high-resolution TEM (Figure ). Figure a,a1 shows the morphologies of GO, where the bending and overlapping of the nanosheets can be observed owing to the hydrogen bonding interactions generated by the functional groups on the GO surface and the π–π stacking of the carbon skeleton . In contrast, the number of edge folds increased in the functionalized GO nanosheets, indicating the increased activity of the modified material.…”