Revealing Factors Governing Self-Assembly Morphology of Fatty Acid on Graphene Synthesized by Surfactant-Assisted LPE: A Joint MD, SAPT(DFT), and Experimental Study

Abstract

The production of graphene nanosheets from graphite with the assistance of biological molecules in water medium as well as understanding the morphology of the resulting self-assembly are important in fields of drug delivery, cell imaging, and photothermal therapy. Hence, in this contribution, we have applied docosahexaenoic acid (DHA) fatty acid to disperse graphite. The morphology of self-assembly on the graphene surface and the factors tailoring the morphology were surveyed in light of classical molecular dynamic (MD) and symmetry-adapted perturbation theory (SAPT). The factors such as surface density, environment pH, substrate size, and number of layers were taken into account. The results show that the decrease in pH transmutes the nature of the classical electrostatic interaction between the surfactants from repulsion to attraction, leading to a decline in the stability of the colloidal systems. When the lateral size of the graphene sheet is three times larger than the length of DHA, hemicylinder structures with a 3.5−4 nm width are formed, which is in excellent agreement with AFM results. The simulation of the effect of number layer reveals that the LPE cannot be initiated without ultrasonic assistant. An arsenal of experimental methods including HR-TEM, TEM, AFM, XPS, UV−vis, and zeta potential confirms the existence of colloidal systems with graphene sheet. The dispersion of graphene using DHA largely preserves the intrinsic chemical structure of graphene. This combined experimental and computational study will be a valuable contribution to the dispersion of graphene by means of fatty acids, which could be utilized in medical purposes.

Taking a look accurately at the alteration of interfacial asphaltene film exposed to the ionic surfactants as demulsifiers

“…Density is one of the critical physical quantities to depict the system content distribution 30 , 31 . Therefore, the density profile in the direction of the Z-axis is utilized to determine the transformation of interfacial ASP film based on the contents distribution variation 20 , 32 .…”

“…The TIP3P model was implemented on the water molecules 19 . The simulations were performed by means of NAMD 20 . CHARMM General Force Field (CGenff) was employed for all contents of the system 21 .…”

Influence of Adsorption Energy in Graphene Production via Surfactant-Assisted Exfoliation of Graphite: A Graphene-Dispersant Design

“…UV–vis spectroscopy has been used to investigate graphene dispersions prepared with different dispersants . The UV–vis absorption in graphene is mainly due to the π → π* CC plasmon transition at λ max < 300 nm. , However, the absorbance at λ > 500 nm is flat, but the optical density is dependent on concentration. As a result, this latter part of the spectrum is commonly used to determine the concentration of the graphitic materials present inside the colloidal dispersion system …”

“…To overcome this challenge, surface modifiers such as surfactants are usually used. Various types of surfactants, including ionic, − nonionic, , gemini, and zwitterionic surfactants, have been widely employed or studied to disperse and stabilize graphene in aqueous media. Generally, in similar experimental conditions for different surfactants, the more the surfactant dispersing proficiency, the larger the graphene concentration produced.…”

Graphene Oxide-Modified Aramid Fibers for Reinforcing Epoxy Resin Matrixes

“…Over the past few years, as impacted by the surface effect, volume effect, quantum size effect, and macroscopic quantum tunneling effect, nanomaterials have been extensively employed in the modification of the AF to enhance the interface properties between the AF and matrix. − At present, considerable studies are focusing on the grafting of nanoparticles, nanotubes, nanosheets, and other nanocomponents to the surface of the AF to prepare multiscale reinforcement, thereby more effectively improving the interface bonding between fiber and resin. − In particular, graphene oxide (GO) nanosheets have been effective in modifying fibers to enhance the performance of the interface with the matrix. For instance, Jiang et al grafted GO on the carbon fiber surface by using electrochemical oxidation to improve the mechanical properties of its epoxy composite (CF/EP).…”