title: Ultradry Carbon Dioxide-in-Water Foams with Viscoelastic Aqueous Phases.
abstract: For foams with ultra low water contents, the capillary pressure is very large and induces rapid drainage that destabilizes the aqueous lamellae between the gas bubbles. However, we show that high-pressure CO2-in-water foams can be stabilized with a viscoelastic aqueous phase composed of entangled wormlike micelles, even for extremely high CO2 volume fractions ϕ of 0.95 to 0.98; the viscosity of these ultradry foams increased by up to 3-4-fold, reaching more than 100 cP relative to foams formed with conventional low viscosity aqueous phases. The foam morphology consisted of fine ∼20 μm polyhedral-shaped CO2 bubbles that were stable for hours. The wormlike micelles were formed by mixing anionic sodium lauryl ether sulfate (SLES) with salt and a protonated cationic surfactant, as shown by cryogenic transmission electron microscopy (cryo-TEM) and large values of the zero-shear viscosity and the dynamic storage and loss moduli. With the highly viscous continuous aqueous phases, the foam lamella drainage rates were low, as corroborated by confocal microscopy. The preservation of viscous thick lamellae resulted in lower rates of Ostwald ripening relative to conventional foams as shown by high-pressure optical microscopy. The ability to stabilize viscous ultra high internal phase foams is expected to find utility in various practical applications, including nearly "waterless" fracturing fluids for recovery of oil and gas in shale, offering the possibility of a massive reduction in the amount of wastewater.
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Zheng
authors.initials: Z
authors.lastname: Xue
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Andrew J
authors.initials: AJ
authors.lastname: Worthen
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Chang
authors.initials: C
authors.lastname: Da
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Ali
authors.initials: A
authors.lastname: Qajar
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Isaiah Robert
authors.initials: IR
authors.lastname: Ketchum
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Shehab
authors.initials: S
authors.lastname: Alzobaidi
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Chun
authors.initials: C
authors.lastname: Huh
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Maša
authors.initials: M
authors.lastname: Prodanović
authors.affiliation: Department of Chemical Engineering and ‡Department of Petroleum and Geosystems Engineering, University of Texas at Austin , Austin, Texas 78712, United States.
authors.forename: Keith P
authors.initials: KP
authors.lastname: Johnston