ef0c02759_si_001.pdf (436.51 kB)
Self-Assembly of Silica Nanoparticles at Water–Hydrocarbon Interfaces: Insights from In Operando Small-Angle X‑ray Scattering Measurements and Molecular Dynamics Simulations
journal contribution
posted on 2020-10-03, 12:29 authored by Sohaib Mohammed, Hassnain Asgar, Ivan Kuzmenko, Greeshma GadikotaTo achieve tunable controls on the
interactions of siliceous materials in subsurface environments bearing
water and hydrocarbons, it is essential to determine the influence
of hydrocarbon–water interfaces on the self-assembly of the
silica particles. The hydrophilic silica particle have a tendency
to aggregate on the water front of the interface. Self-assembly of
silica nanoparticles proceeds via the migration of these nanoparticles
to the water–hydrocarbon interface followed by aggregation
at the interface. Fractal-like morphologies of assembled silica nanoparticles
at water–hydrocarbon interfaces are observed. Rapid assembly
of the hydrophilic silica nanoparticles at water–hydrocarbon
interfaces corresponds to an overall reduction in the surface tension
of water–toluene and water–heptane systems. These studies
demonstrate the silica aggregation that is the precursor of silica
polymerization, or nucleation and growth is influenced by the presence
of hydrocarbons in subsurface geologic environments. These insights
were derived from in operando ultrasmall and small-angle
X-ray scattering (USAXS/SAXS) measurements, cryo-scanning electron
microscopy (Cryo-SEM) imaging, and classical molecular dynamics simulations.
These studies are intended to inform current and future efforts aimed
at tuning silica reactivity in subsurface geologic environments to
enhance permeability, the design and use of silica-based proppants
to enhance fractures, and the development of effective strategies
to control silica-based scaling behavior in subsurface reservoirs.