Surface modification of carbon black nanoparticles by dodecylamine: Thermal stability and phase transfer in brine medium

Stable aqueous dispersions of carbon black (CB) nanoparticles were prepared by developing a generic bilayer approach to the CB phase-transfer method using commercial Avanel as a surfactant. CB was oxidized using ammonium persulfate, and dodecylamine (DDA) was grafted onto this carbon core using N,N-dicyclohexylcarbodiimide as a coupling agent. The covalent bond between CB and DDA was confirmed by X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, ultraviolet–visible spectroscopy, and thermogravimetric analysis. The average diameter of the primary carbon nanoparticles after chemical modification increased from 15 to 20 nm, as determined by high-resolution transmission electron microscopy. Dispersions of the modified CB was stable in organic solvents and were thermally stable in saline water when Avanel was used as a surfactant. The Avanel coating on the CB particles enabled the design of carbon materials with high colloidal stability, as evidenced by dynamic light scattering measurements and the breakthrough characteristics of the coated material in sandstone rocks.