Steric stabilization of nanoparticles with grafted low molecular weight ligands in highly concentrated brines including divalent ions

Abstract

Whereas numerous studies of stabilization of nanoparticles (NPs) in electrolytes have examined biological fluids, the interest has grown recently in media with much higher ionic strengths including seawater and brines relevant to environmental science and subsurface oil and gas reservoirs. Given that electrostatic repulsion is limited at extremely high ionic strengths due to charge screening, we have identified ligands that are well solvated in concentrated brine containing divalent cations and thus provide steric stabilization of silica nanoparticles. Specifically, the hydrodynamic diameter of silica nanoparticles with grafted low molecular weight ligands, a diol ether, [3-(2,3-dihydroxypropoxy)propyl]-trimethoxysilane, and a zwitterionic sulfobetaine, 3-([dimethyl(3-trimethoxysilyl)propyl]ammonio)propane-1-sulfonate, is shown with dynamic light scattering to remain essentially constant, indicating lack of aggregation, at room temperature and up to 80 °C for over 30 days. An extended DLVO model signifies that steric stabilization is strongly dominant against van der Waals attraction for ∼10 nm particles given that these ligands are well solvated even in highly concentrated brine. In contrast, polyethylene glycol oligomers do not provide steric stabilization at elevated temperatures, even at conditions where the ligands are soluble, indicating complicating factors including bridging of the ether oxygens by divalent cations.

Electrosteric colloidal stabilization for obtaining SrTiO3/TiO2 heterojunction: Microstructural evolution in the interface and photonics properties

“…Thus, H + from surface binds with an OH − from PVA, releasing a H 2 O molecule and the remained SrTiO 3 eO − binds with the remained C + from PVA, generating and SrTiO 3 eOeR bond, being R the carbon chain of the PVA molecule without the hydroxyl, by covalent bonding. As a consequence, PVA molecules covering the particles generate the steric contribution, which are the lines covering the SrTiO 3 particles, that is responsible for avoiding the agglomeration of particles on suspension due to the steric repulsion forces between the polymer chains [24,25].…”

A State-of-the-Art Review of Nanoparticles Application in Petroleum with a Focus on Enhanced Oil Recovery

“…Thus, in a high-salinity environment, modification to the NPs is necessary to maintain the stability which can be achieved by surface modification, ionic control via a surfactant, or a combination of both [89]. Worthen et al [154] reported the stabilization of NPs by anchoring low molecular weight ligands to the NP surface in a high-salinity environment. The authors claimed that the NP stabilization stems from the steric hindrance.…”

Glycerol to lactic acid conversion by NHC-stabilized iridium nanoparticles

“…2) clearly confirmed the presence of isolated and homogeneously dispersed Ir NPs featured by a mean diameter (d m ) of 1.8 nm. The efficient separation of the NPs from each other is due to the steric repulsion of NHC ligands located on different Ir NPs' surfaces [47,48].…”