Hybrid smart emulsification systems are highly applicable in manipulating oil-in-water (O/W) droplets. Herein, novel switchable block polymers containing both zwitterionic and tertiary amine pendent groups were designed and synthesized to combine with charged silica particles to stabilize the O/W emulsion responsive to pH. This study was carried out in O/W emulsions stabilized with the polymer and silica particles under different pH conditions. The emulsion system was also simulated using molecular dynamics simulation to reveal the mechanism at molecular levels, thus gaining insight into the relationships between the emulsifying properties and the molecular interaction of the mixed system. Upon acidification of the continuous aqueous phase, protonated polymers with excellent hydrophilicity were induced by charged silica particles to cause rapid emulsion coalescence. In alkaline media, the mixed system conversely stabilized the O/ W emulsions, cutting polymer consumption by over three-quarters. The emulsification and demulsification can be switched alternately by tuning the pH conditions. The applications exhibited excellent efficiency in separating heavy oil/water emulsions and proved the high conversion rate in emulsion polymerization. Overall, with this novel strategy to relieve tedious modifications on particle surfaces and massive consumption of polymers, the designed responsive emulsification systems can impart intelligent and controllable chemical reactivity to emulsions on demand in a more affordable and sustainable way.
Conventional water flooding strategy has limited the further development of heavy oil recovery due to the lower displacement efficiency. In this work, a potential zwitterionic/anionic surfactant system to enhance heavy oil recovery in the high salinity was proposed through low budget and feasible mixing. We evaluated the capabilities of the mixed surfactant systems consisting of zwitterionic cocoamidopropyl sulfonate betaine (CSB) and anionic sodium dodecyl benzene sulfonate (SDBS) in terms of surface tension, interfacial tension (IFT), emulsion size distribution, emulsion stability, apparent viscosity, emulsion viscoelasticity, viscosity reduction, and recovery efficiency. The IFT could substantially reduce to an ultralow level (<10 −2 mN/m) at a higher salinity. The smaller droplets (0.1−3 μm) were formed to stabilize the heavy oil emulsions. The viscoelasticity test confirmed that the intensity of the interface film was enhanced because SDBS/CSB molecules could coabsorb at the heavy oil−water interface in a most closely packed arrangement. Furthermore, the water flooding experiments with different surfactant systems were also implemented to affirm the great potential of the synergetic surfactant systems for heavy oil recovery.
Intelligent polymers responsive to the environment have aroused widespread interest in many applications of materials and interfaces. However, sensitive control of the oil-water interface remains a major challenge, using reversible self-assembly of macromolecules induced by external stimuli. Here, we synthesized a new amphiphilic triblock copolymer responsive to pH and UV light via reversible addition–fragmentation chain transfer (RAFT) aqueous polymerization. Poly(methacrylic acid) (PMAA) acts as the hydrophilic block; poly(N, N-dimethyl aminoethyl methacrylate) (PDMAEMA) and poly(methacrylamide azobenzene) (PMAAAB) are the hydrophobic blocks with responsiveness. The as-synthesized polymer was measured regarding UV–vis transmittance and contact angle to verify the tunable amphiphilicity and wettability by the double stimulation. The newly developed dual-responsive polymer was applied for oil/water separation and controlled dye release. With the synergic stimulation of pH and UV light, efficient separation for oil-in-water emulsions (separation efficiency: 66.8% in 15 min) and excellent desorption for adsorbed dyes (desorption efficiency: 93.8% in 15 min) are achieved.
Intelligent polymers responsive to the environment have aroused widespread interest in many applications of materials and interfaces. However, sensitive control of the oil-water interface remains a major challenge, using reversible self-assembly of macromolecules induced by external stimuli. Here, we synthesized a new amphiphilic triblock copolymer responsive to pH and UV light via reversible additionfragmentation chain transfer (RAFT) aqueous polymerization. Poly(methacrylic acid) (PMAA) acts as the hydrophilic block; poly(N, N-dimethyl aminoethyl methacrylate) (PDMAEMA) and poly(methacrylamide azobenzene) (PMAAAB) are the hydrophobic blocks with responsiveness. The as-synthesized polymer was measured regarding UV-vis transmittance and contact angle to verify the tunable amphiphilicity and wettability by the double stimulation. The newly developed dual-responsive polymer was applied for oil/water separation and controlled dye release. With the synergic stimulation of pH and UV light, e cient separation for oil-in-water emulsions (separation e ciency: 66.8% in 15 min) and excellent desorption for adsorbed dyes (desorption e ciency: 93.8% in 15 min) are achieved.
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