Unexpected excellent under-oil superhydrophilicity of poly(2-(dimethylamino)ethyl methacrylate) for water capture from oil and water-induced oil self-dewetting

Realizing the Efficient Dissolution of Drag Reducer upon pH-Induced Demulsification of Inverse Polymer Emulsion

“…In contrast to conventional hydraulic fracturing techniques, slick-water fracturing systems allow for more efficient flow conductivity and lower losses. , Drag reducers (DRs) are not only important polymer additives in slick-water fracturing systems but also reduce frictional energy losses within the pipe and fractures during high-volume and high-displacement fracturing, thereby effectively transporting proppant to the formation. − Currently, drag reducers exist mainly in polymer-based forms, including both powder and emulsion . In some studies, it was found that the slow dissolution of powdered polymers in water results in a low drag reduction efficiency, and inadequate dissolved powders result in a mass of polymer lumps that cause problems such as clogging of pipes. , Emulsion polymers can dissolve and release quickly in water, which not only improves the rate of drag reduction but also serves as a carrying fluid for various types of proppants. , However, the addition of a hydrophilic surfactant is required to destabilize the emulsion so that the emulsion polymers can be released by complete dissolution in solution. , Therefore, the selection of a suitable surfactant is critical in determining the release of the polymer and must not affect the stability of the polymer emulsions . To solve the above problems, a stimulus-responsive surfactant should be designed that can undergo structural changes in response to external stimulus conditions, resulting in the opposite turn of the emulsion .…”

Under-Oil Superhydrophilic/Superhydrophobic Janus Nanofibrous Membrane for Highly Efficient Separation of Surfactant-Stabilized Water-in-Oil Emulsions

“…For oil–water separation, under-oil superhydrophilicity can be an alternative to the hydrophilic–oleophobic property, because it also enables the antioil-fouling function by making water to replace oils that were attached on the membrane surface, and it also is able to promote the demulsification of water-in-oil emulsions, because of its stronger affinity to water than that to oils. − Compared to the hydrophilic–oleophobic property, under-oil superhydrophilicity has an obvious advantage of eliminating the use of a fluorinated moiety. So far, although there appear to be several under-oil superhydrophilic materials, including cellulose-based porous materials, , desert sand, fumed silica-coated metal felt, metal organic frame (MOF)-coated stainless-steel mesh, poly­(2-(dimethylamino)­ethyl methacrylate)-coated fabric, and electrospun membrane of deacetylated cellulose acetate, it is still challenging to achieve the under-oil superhydrophilicity, because the replacement of the solid–oil interface (lower interfacial tension) by a solid–water interface (higher interfacial tension) is thermodynamically unfavorable.…”

“…18−20 Compared to the hydrophilic− oleophobic property, under-oil superhydrophilicity has an obvious advantage of eliminating the use of a fluorinated moiety. So far, although there appear to be several under-oil superhydrophilic materials, including cellulose-based porous materials, 21,22 desert sand, 23 fumed silica-coated metal felt, 24 metal organic frame (MOF)-coated stainless-steel mesh, 25 poly(2-(dimethylamino)ethyl methacrylate)-coated fabric, 26 and electrospun membrane of deacetylated cellulose acetate, 27 it is still challenging to achieve the under-oil superhydrophilicity, because the replacement of the solid−oil interface (lower interfacial tension) by a solid−water interface (higher interfacial tension) is thermodynamically unfavorable.…”