Segregation of Amphiphilic Polymer-Coated Nanoparticles to Bicontinuous Oil/Water Microemulsion Phases

Abstract

Polymer-coated nanoparticles are interfacially active and have been shown to stabilize macroscopic emulsions of oil and water, also known as Pickering emulsions. However, prior work has not explored the phase behavior of amphiphilic nanoparticles in the presence of bicontinuous microemulsions. Here, we show that properly designed amphiphilic polymercoated nanoparticles spontaneously and preferentially segregate to the bicontinuous microemulsion phases of oil, water, and surfactant. Mixtures of hydrophilic and hydrophobic chains are covalently grafted onto the surface of oxidized carbon black nanoparticles. By sulfating hydrophilic chains, the polymer-coated nanoparticles are stable in the aqueous phase at salinities up to 15 wt % NaCl. These amphiphilic, negatively charged polymer-coated nanoparticles segregate to the bicontinuous microemulsion phases. We analyzed the equilibrium phase behavior of the nanoparticles, measured the interfacial tension, and quantified the domain spacing in the presence of nanoparticles. This work shows a novel route to the design of polymer-coated nanoparticles which are stable at high salinities and preferentially segregate to bicontinuous microemulsion phases.

Nanotechnology in Enhanced Oil Recovery

“…Actually, in the heavy oil reservoir, polymer-coated nanoparticles can change the pH conditions of the reservoir and cause recovery of heavy oil, which is shown in Figure 4. [40] and (d) schematic of oil-water microemulsion phases with polymer-coated NP additives [41].…”

“…Relationships between the temperature, initial wettability and additional oil recovery and the nanofluid flooding (nano-EOR) process were investigated. [40] and (d) schematic of oil-water microemulsion phases with polymer-coated NP additives [41].…”

“…Figure 4. Schematic of (a) the use of polymer-coated NP additives to recover heavy oil trapped in porous media, (b) the demulsification of oil-in-water emulsions with changes in solution pH, (c) wettability alteration by polymer-coated NPs[40] and (d) schematic of oil-water microemulsion phases with polymer-coated NP additives[41].…”

Natural Halloysites-Based Janus Platelet Surfactants for the Formation of Pickering Emulsion and Enhanced Oil Recovery

“…The structures of Pickering emulsions and foams are stabilized with solid particles instead of molecular surfactants. Compared to emulsions stabilized by conventional molecular surfactants, Pickering emulsions are more stable due to their resistance to coalescence and Oswald ripening 3–5 , which makes them perfect candidates for industrial application in foods 6,7 , mining 8,9 , pharmaceuticals 10 and cosmetics 11 . In related research, a variety of nanoparticles with different morphologies have been used to stabilize Pickering emulsions, such as zero-dimensional nanoparticles 12 , one-dimensional nanowires 13 , and one-dimensional nanotubes 14 .…”

Mechanical phase inversion of Pickering emulsions via metastable wetting of rough colloids

“…Colloidal particles and liquid interfaces bear significant importance in addressing fundamental scientific questions and present many opportunities in industrial applications, ranging from food 1 to heavy oil processing. 2,3 Since the seminal observations of Ramsden and Pickering, 4,5 partially wetting colloidal particles trapped at liquid interfaces have been proposed as excellent emulsion and foam stabilizers. Depending on their wettability, particles larger than a few nanometers can have energies binding them to a fluid interface that easily exceed thermal energy by several orders of magnitude.…”