Rheological properties of wormlike micelles formed in the sodium oleate/trisodium phosphate aqueous solution

Formulation of an Encapsulated Surfactant System, ESS, via β-CD Host–Guest Interactions to Inhibit Surfactant Adsorption onto Solid Surfaces

“…69,70 These observations are in agreement with previous studies on the rheological properties of wormlike micelles of anionic surfactants. 28 This dynamic viscosity data allows us to speculate that for in situ shear rates ≥ 24 rad/s −1 the dynamic viscosity of the Non-ESS microemulsion would be approximately <21 cP, while the dynamic viscosity of the ESS would be <13 cP (Figure 6d). The substantial shear-thinning flow behavior and suitable values of dynamic viscosities (i.e., viscosity values that are not too high and/or too low relative to the viscosity of the oil) ensure stable microemulsion systems that effectively propagate through the sand-packs, forming a stable displacement front that displaces oil more effectively with a low risk of microemulsion phase fingering and/or trapping within the porous media.…”

“…In Figure c, the Non-ESS microemulsion shows the behavior of an viscoelastic fluid with tan δ > 1 or G ″ > G ′ in the entire range of angular frequencies studied; thus, “the viscous modulus, G ″, completely dominates the elastic modulus, G ‴, while the loss-factor (tan δ = G ″/ G ′) curve of the ESS microemulsion transitions from a viscoelastic liquid behavior ( G ″ > G ′ or tan δ > 1) at lower shear rates to a well-defined viscoelastic gel behavior ( G ′ > G ″ or tan δ < 1) at higher shear rates. This performance indicates that at higher shear rates the ESS microemulsion displays the behavior of a stronger self-assembly micellar network structure. , In addition, these observations reveal the higher elasticity of the ESS microemulsion relative to the Non-ESS system.…”

“…This performance indicates that at higher shear rates the ESS microemulsion displays the behavior of a stronger self-assembly micellar network structure. 28,69 In addition, these observations reveal the higher elasticity of the ESS microemulsion relative to the Non-ESS system. Figure 6d compares the dynamic viscosity (i.e., real part of the complex viscosity), η′, as a function of angular frequency [rad/s] for both microemulsion systems, which display a shearthinning flow behavior that is "typical of complex surfactant systems, with a high degree of emulsification and emulsion stability".…”

“…In EOR applications, anionic surfactants are commonly employed due to their low manufacturing costs, relative low adsorption to the negatively charged sandstone rocks (i.e., under neutral-to-basic pH) via electrostatic repulsions, efficient reduction of IFT, and relative stability at reservoir conditions. Furthermore, anionic surfactants can be customized using polar moieties that are stable at high reservoir temperatures, as is the case of sulfonate head polar groups. ,,,,,,,,− The main downside is that the adsorption of anionic surfactants is accelerated by the presence of salts and divalent cations, which is inherent in oil reservoir formations. − ,,,,, Some of the mechanisms that contribute to the adsorption of surfactants onto rock solid surfaces include electrostatic attractions, hydrogen bonding, hydrophobic bonding, van der Waals interactions, ion exchange, adsorption by the polarization of π electrons, adsorption dispersion forces, and so on. , In the case of anionic surfactants, the main adsorption mechanism is electrostatic interactions between the rock surface and surfactants. , Furthermore, Suresh et al suggest that surfactant “adsorption usually occurs in the form of a monolayer at lower concentrations, and then to several layers when surfactant concentration increases” …”

Preparation and Characterization of Polymeric Surfactants Based on Epoxidized Soybean Oil Grafted Hydroxyethyl Cellulose

“…Hydroxyl 36 groups always have chemical handles that can react with hydrophobic chains 37 containing epoxide, halide, acyl halide, isocyanate or anhydride for the preparation of 38 amphiphilic cellulose. Polymeric surfactants based on hydroxyethyl cellulose (HEC) 39 were prepared by the reaction of a long-chain terminal epoxide with the hydroxyl 40 groups of HEC in an alkaline slurry. 9 Partial hydrophobization of carboxymethyl 41 cellulose with C12-C18 alkyl halides was carried out in the presence of sodium 4 co-monomer styrene (St) in aqueous solution.…”