Polymeric Surfactant Concentration Research Articles

Block copolymer penetration into an asphaltene film as a mechanism for water-in-crude oil emulsion break-up

During crude oil extraction, asphaltene-stabilized water-in-oil emulsions are formed and make the dewatering a challenging task. Demulsifiers (surface active agents), are typically used to destabilize the emulsion and facilitate the coalescence of water droplets. The demulsification mechanism of asphaltene-stabilized water-in-toluene emulsions by an ethylene oxide-propylene oxide-ethylene oxide (EO37─PO56─EO37) based block copolymer was studied. The performance of the demulsifier was assessed by bottle tests and the interfacial properties were determined by means of interfacial tension, Langmuir trough and contact angle measurements. From bottle tests experiments, the demulsifier showed the best performance at 3.85 µM in the water phase. A concentration dependent disruption of an asphaltene monolayer onto an aqueous polymeric surfactant subphase, was observed by means of Langmuir trough experiments. An interesting breakpoint was found at 0.154 µM aqueous polymeric surfactant concentration in the surface pressure-area isotherm, which is attributed to the formation of a new phase. Contact angle measurements of drops of aqueous polymeric surfactant solution onto asphaltene films showed that, at increasing polymeric surfactant concentration, the contact angle diminished to a threshold value. A direct interaction of block copolymer with asphaltene is proposed as a mechanism to account for the destabilization of water-in-oil emulsions.

Synthesis of polymeric surfactant from palm oil methyl ester for enhanced oil recovery application

Methyl ester sulfonate (MES) is an anionic surfactant derived from natural oils. Polymers are large molecules composed of many repeated units that increase viscosity as a mobility control. Therefore, polymer and surfactant can be reacted into one substance as an alternative for enhanced oil recovery (EOR) application. The principle of this research is to graft sulfonate groups from MES into the polymer chain. Based on the experiments, the best result of polymerization was obtained at a mole ratio of 1:0.3 MES to acrylamide. Based on the interfacial tension (IFT) measurement, the IFT value decreased from 8.6 to 2.3 mN/m before and after the addition of polymeric surfactant respectively. The synthesis of polymeric surfactant obtained a yield of 1384.79%. Polymeric surfactant is potential candidates to change the initial oil-wet state of the quartz surface to water-wet based on wettability alteration study. According to thermal analysis and emulsification behavior, this polymeric surfactant was thermally stable under the desired reservoir temperature and was able to emulsify crude oil. The adsorption study showed that the adsorption onto the rock surface increased when the polymeric surfactant concentration was increased in the system. Core flooding experiments showed an increase in oil recovery in different concentrations of polymeric surfactant. Although the IFT value of polymeric surfactant is not very low, it has the potential as an alternative surfactant for EOR applications.

Study on the Influencing Factors of the Emulsion Stability of a Polymeric Surfactant Based on a New Emulsification Device

Polymeric surfactant flooding is an effective method to improve oil recovery, and the stability of the emulsion is closely related to the effect of surfactant flooding. The preparation method for a surfactant-stabilized emulsion is relatively simple, and the emulsion produced by the existing device cannot simulate the real formation conditions. To better simulate the emulsification of polymeric surfactant during formation and to study the influencing factors of emulsion stability, a new sieve plate rotary emulsification device was used to prepare emulsions instead of the traditional high-speed shear emulsifier, and the stability of emulsions prepared by different methods was compared. The parameters of the device were optimized by determining the water content, particle size, and Turbiscan Stability Index TSI (stability parameter) of the emulsion. The factors affecting the stability of the emulsion were studied by using the optimized experimental device. The results showed that the optimized parameters of the sieve plate rotary emulsification device were 5 sieve plates, diameter of 1 mm, and emulsification time of 60 min. The stability of the emulsion prepared by the new device was better than that of the emulsion prepared by the traditional high-speed stirrer, which can be attributed to the more abundant contact and mix of oil and surfactant solution. Meanwhile, as the polymeric surfactant concentration, salinity, and water–oil ratio increased, the stability of the polymeric surfactant emulsion increased. The results of this study provide a theoretical basis and guidance for better simulation of polymeric surfactant migration and emulsification during formation.

Interfacial behavior of oil/oil and oil/water soluble binary surfactants and their effect on stability of highly concentrated W/O emulsions

Instability of highly concentrated water-in-oil emulsions which contain a metastable inorganic salt solution in a form of drops arises from the crystallization of salt in the dispersed phase, both on the shelf and under high shear. In this work the interfacial properties of two binary mixtures of oil/oil soluble and oil/water soluble surfactants with different molar ratios were studied to determine their effect on the stability of manufactured emulsions. The two mixed surfactants used were mainly poly (isobutenyl) succinic anhydride (PIBSA)-based surfactant with either sorbitan monooleate (SMO) (oil/oil soluble) or with polyoxyethylene sorbitan monooleate (Tween 80) (oil/water soluble). Interfacial studies showed completely opposite behavior of these two mixtures with changing concentration of polymeric surfactant. A synergetic effect between PIBSA-Mea and Tween 80 molecules was evident. PIBSA/Tween 80 emulsions exhibited better shelf stability than the PIBSA-Mea/SMO mixtures due to the efficiently packed interfacial film produced by this synergetic binary surfactant mixture. In addition, a significant improvement in stability under high shear conditions was achieved with the oil/water soluble PIBSA/Tween 80 mixture. The results showed that the interfacial study are important for the understanding of instability due to crystallization in emulsions with an oversaturated dispersed phase

Linear-, Cyclic-, and Multiblock Amphiphilic Polyelectrolytes as Surfactants in Emulsion Polymerization: Role of Topological Structure

Combining atom transfer radical polymerization (ATRP) and “click” chemistry, a set of well-defined amphiphilic block copolymers poly(n-butyl acrylate)-b-poly(acrylic acid) (PnBA20-PAA85) with a similar chemical component, but different topological structures, i.e., linear-, cyclic-, and multiblock structures, were successfully prepared, characterized (size exclusion chromatography (SEC), FT-IR and 1H NMR), and used as surfactants in emulsion polymerization. Our further transmission electron microscopy (TEM) and laser light scattering (LLS) characterization of the resultant latex particles demonstrates all the surfactants with different topologies can effectively stabilize the latex particles but no significant difference among the solids contents was observed. Moreover, we have, for the first time, experimentally established the quantitative relation between the final number of latex particles (Np) and the concentration of polymeric surfactant with different topologies (C), i.e., Np = kCα, and the order of our measured exponent α is as follows: αmulti(1.10) > αlinear(0.81) ≥ αcyclic(0.73), indicating cyclic surfactant molecules behave more like small-molecule surfactants attributed to its strongest unimers extraction and diffusion ability; in contrast, multiblock surfactant molecules can act as seeds to directly nucleate to create latex particles. In addition, Np,multi > Np,linear ≥ Np,cyclic at higher concentration, and Np,linear > Np,cyclic ≥ Np,multi at lower concentration was observed. Similar results (αmulti(1.02) > αlinear(0.65) ≥ αcyclic(0.58)) were also observed when polystyrene-b-poly(acrylic acid) (PS9–PAA60) copolymers were used as surfactants. Further aqueous SEC characterization shows the broad size distribution of our micellar solution has no effect on obtaining narrowly distributed latex particles. Finally, interfacial tension measurement of the micellar solution indicates, compared to multiblock structure, the rate of adsorption at a hydrophobic interface is much faster for linear and cyclic-block structures, agreeing with our observed order of exponent α.

Soy-Based Surface Active Copolymers As a Safer Replacement for Low Molecular Weight Surfactants

Environmentally friendly soybean-based polymeric surfactants (SBPS) were synthesized using cationic polymerization of a vinyl ether monomer derived from soybean and tri(ethylene glycol) ethyl vinyl ether. The ability of SBPS to form micelles that solubilize hydrophobic molecules has been shown. Micellar “capacity” (size of micellar interior) increased with increasing polymeric surfactant concentration and temperature. The obtained results provide evidence for potential use of SBPS as a safer replacement for low molecular weight surfactants in the solubilization of poorly soluble ingredients in cosmetics. The macromolecules developed can be used as both a surface active agent and an additive that enhances the surface activity of low molecular weight surfactants (for example, anionic sodium lauryl sulfate) in personal-care products.

An experimental study on ASP process using a new polymeric surfactant

This paper presents an alternative chemical formulation using a new polymeric surfactant to improve the conventional alkali/surfactant/polymer (ASP) flooding. It is a one-component system for interfacial tension reduction and viscosity control. To simulate the conventional ASP flooding, the performance of the polymeric surfactant was studied in the absence and presence of sodium carbonate. The most outstanding feature of the new polymeric surfactant lies in its viscosity insensitivity towards an increasing alkali concentration up to 1.2 wt%. This feature makes the new formula superior to the conventional ASP process. A combination of alkali and surfactant with a concentration of 0.8 and 0.4 wt% was found to significantly reduce the interfacial tension while maintaining the desired solution viscosity. The optimal polymeric surfactant concentration was then validated in coreflood experiments using different surfactant concentrations. Using the optimum surfactant and alkali concentrations, tertiary oil recovery could reach 16.3 % of the original oil in place by injecting a 0.5 pore volume of the formulated slug. This makes the new polymeric surfactant promising because it has structural feature that can be modified to give a width range of interfacial tension reduction and viscosity control to suit reservoir conditions.

Chiral micellar electrokinetic chromatography‐atmospheric pressure photoionization of benzoin derivatives using mixed molecular micelles

In the present work we report, for the first time, the successful on-line coupling of chiral MEKC (CMEKC) to atmospheric pressure photoionization MS (APPI-MS). Four structurally similar neutral test solutes (e.g. benzoin (BNZ) derivatives) were successfully ionized by APPI-MS. The mass spectra in the positive ion mode showed that the protonated molecular ions of BNZs are not the most abundant fragment ions. Simultaneous enantioseparation by CMEKC and on-line APPI-MS detection of four photoinitiators, hydrobenzoin, BNZ, benzoin methyl ether, benzoin ethyl ether, were achieved using an optimized molar ratio of mixed molecular micelle of two polymeric chiral surfactants (polysodium N-undecenoxy carbonyl-L-leucinate and polysodium N-undecenoyl-L,L-leucylvalinate). The CMEKC conditions, such as voltage, chiral polymeric surfactant concentration, buffer pH, and BGE concentration, were optimized using a multivariate central composite design (CCD). The sheath liquid composition (involving %v/v methanol, dopant concentration, electrolyte additive concentration, and flow rate) and spray chamber parameters (drying gas flow rate, drying gas temperature, and vaporizer temperature) were also optimized with CCD. Models built based on the CCD results and response surface method were used to analyze the interactions between factors and their effects on the responses. The final overall optimum conditions for CMEKC-APPI-MS were also predicted and found in agreement with the experimentally optimized parameters.

Thin wetting film from aqueous solution of polyoxyalkylated DETA (Diethylenetriamine) polymeric surfactant

Thin wetting films from aqueous solutions of the polymeric surfactant polyoxyalkylated diethylenetriamine (DETA), have been studied on hydrophilic SiO 2-glass surface. The wetting (receding) contact angles θ r of the solution on the glass surface have been measured, using the sessile drop method. Also the contact angle θ aq of a drop of doubly distilled water on the same glass surface pre-treated with DETA polymeric surfactant solution has been measured. The receding contact angles θ r versus polymeric surfactant concentration C s curves showed a maximum at θ r ≈ 22° in the concentration range of 10 −6–2 × 10 −5 mol dm −3 DETA. The equilibrium thickness h of wetting films from DETA aqueous solution on hydrophilic SiO 2-glass surface, pre-treated with surfactant solution, has been measured using the micro-interferometric method at various concentrations, C s. At very low C s (between 10 −11 and 10 −8 mol dm −3) the h-values are almost constant, then they increase with increasing C s reaching a maximum at 1.5 × 10 −6 mol dm −3, after which they decrease with further increase in C s. Both θ r and h exhibit largest values in the concentration range between 2 × 10 −6 and 2 × 10 −5 mol dm −3 DETA. The analysis of the results obtained shows that the stability of the wetting films from aqueous solutions of DETA is determined by the electrostatic, steric, and hydrophobic components of disjoining pressure, respectively by the adsorption and orientation of the polymeric DETA molecules on the SiO 2-glass surface.

Emulsion polymerization of styrene with amphiphilic random copolymer as surfactant: Predominant droplet nucleation

AbstractAmphiphilic random copolymer consisting of monomeric units of poly (butyl acrylate) and poly (maleic acid salt) was synthesized and characterized. The emulsion polymerization kinetics of styrene stabilized by this copolymer was investigated. The influencing factors, including polymeric surfactant concentration, initiator concentration and polymerization temperature, were systematically studied. The kinetic data show that the polymerization rate (RP) increased with the increase of the polymeric surfactant concentration ([S]) and polymerization temperature (T). At the higher [S], droplets nucleation and micelle nucleation coexisted in the polymerization system; at the lower [S], only the droplets nucleation process existed. The polymerization did not follow Smith‐Ewart Case II kinetics. Dynamic light scatter and transmission electron microscope were utilized to measure the sizes and shapes of the particles, respectively. It would be speculated that a kind of large heterogeneous particles with multiple‐active‐sites was formed in the polymerization system. The increasing of RP with increasing initiator concentration ([KPS]) was rapid at a medium [KPS], but the slowly increasing was observed at a lower or higher [KPS]. It was attributed to the barrier effect of the polymeric surfactant around the monomer droplets. The polymerization activation energy was 60.29 kJ/mol. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

Wetting films from aqueous solutions of polymeric surfactants on hydrophobic solid surface

Wetting films from aqueous solutions of three different polymeric surfactants (hydrophobically modified inulin with two degrees of substitution, INUTEC SP1 and HMI-B, and hydrophobically modified polyacrylate, EFKA) were obtained on hydrophobic glass surfaces with different degrees of hydrophobicity. The equilibrium film thickness h was measured as a function of polymeric surfactant concentration C. For surfaces with low degree of hydrophobicity h increased, whereas for surfaces with high hydropobicity h decreased, with increase of C SP1. For HMI-B with higher degree of substitution h remained virtually constant for surfaces with low degree of hydrophobicity, while for high degree of hydrophobicity h increased with increase of C HMI-B . With EFKA h decreased with increase of polymeric surfactant concentration. The addition of 0.05 M NaCl caused a significant reduction in film thickness. A tentative explanation of the differences between the three polymeric surfactants was given in terms of the electrostatic interaction contribution. Two main features have been established: (i) stable films exist at high polymeric surfactant concentration and low degree of hydrophobicity of the solid surface; (ii) unstable films that rupture at low polymeric surfactant concentration and high degree of hydrophobicity of the solid surface.

Stabilization of Latex Dispersions Using a Graft Copolymer of Inulin Based Surfactants

Polystyrene (PS) latex dispersions were prepared by surfactant-free emulsion polymerization. Poly(methyl methacrylate) (PMMA) latex dispersions were prepared using the same procedure except by adding INUTEC SP1 as emulsifier. The two latex dispersions were characterized by photon correlation spectroscopy (PCS) to obtain the average particle size and the polydispersity index. The stability of these latex dispersions was measured by determination of the critical coagulation concentration (CCC) of three electrolytes, namely, NaCl, CaCl2, and Al2(SO4)3. The CCC was 0.375 mol·dm-3 for NaCl, 0.007 mol·dm-3 for CaCl2, and 0.0004 mol·dm-3 for Al2(SO4)3. A polymeric surfactant, namely, a graft copolymer of polyfructose on which alkyl groups were grafted to the backbone, were added to latex dispersions and their stability was investigated. On addition of this polymeric surfactant, the stability of the latex dispersions was significantly increased and the CCC became very high above a critical polymer concentration. For the PS latex, the CCC of CaCl2 was higher than 4.3 mol·dm-3 when the polymeric surfactant concentration was 0.25 wt %. The results could be rationalized in terms of the enhanced steric repulsion resulting from the adsorption of the graft copolymer. It was assumed that the molecule produces large “loops” of polyfructose between the adsorbed alkyl groups, forming a hydrated layer thickness of approximately 4 nm. In addition, these polyfructose chains were still hydrated even in the presence of high electrolyte concentrations.

Micellar electrokinetic chromatography of polychlorinated biphenyl congeners using a polymeric surfactant as the pseudostationary phase

Micellar electrokinetic chromatography (MEKC) of highly hydrophobic compounds is generally difficult using sodium dodecyl sulfate micellar solutions. The polymeric surfactant, polysodium undecyl sulfate (poly-SUS) has been used to separate moderately to highly hydrophobic polychlorinated biphenyl (PCB) congeners by MEKC in the absence of cyclodextrins. Parameters such as concentration of acetonitrile (ACN), polymeric surfactant concentration, and the effect of pH were examined. Optimum MEKC conditions to get baseline resolution of nine PCBs was 7.5 m M borate in 40% (v/v) ACN fraction buffered at pH 9.2 using 0.5% (w/v) poly-SUS. The applied voltage was 30 kV and the temperature was maintained at 25°C. Elution order for each PCB congener was found to be dependent on the degree of chlorination and hydrophobic character.