Enhanced oil recovery by nonionic surfactants considering micellization, surface, and foaming properties

Surfactants for enhanced oil recovery are important to study due to their special characteristics like foam generation,lowering interfacial tension between oleic and aqueous phases,and wettability alteration of reservoir rock surfaces.Foam is a good mobility control agent in enhanced oil recovery for improving the mobility ratio.In the present work,the foaming behavior of three nonionic ethoxylated surfactants,namely Tergitol 15-S-7,Tergitol 15-S-9,and Tergitol 15-S-12,was studied experimentally.Among the surfactants,Tergitol 15-S-12 shows the highest foamability.The effect of Na Cl concentration and synthetic seawater on foaming behavior of the surfactants was investigated by the test-tube shaking method.The critical micelle concentrations of aqueous solutions of the different nonionic surfactants were measured at 300 K.It was found that the critical micelle concentrations of all surfactants also increased with increasing ethylene oxide number.Dynamic light scattering experiments were performed to investigate the micelle sizes of the surfactants at their respective critical micelle concentrations.Core flooding experiments were carried out in sand packs using the surfactant solutions.It was found tha t22% additional oil was recovered in the case of all the surfactants over secondary water flooding.Tergitol 15-S-12exhibited the maximum additional oil recovery which is more than 26%after water injection.

Synthesis of Cardanol Sulfonate Gemini Surfactant and Enthalpy-Entropy Compensation of Micellization in Aqueous Solutions

A novel cardanol sulfonate Gemini surfactant with high surface properties was synthesized by cashew phenol, 1,3-dibromopropane and chlorosulfonic acid through three steps procedure of etherification, sulfonation and neutralization. A surface tension method was employed to investigate the thermo-dynamic properties of micellization in aqueous solution for cardanol sulfonate Gemini surfactant synthesized in laboratory. As a result, the micellization of cardanol sulfonate Gemini surfactant in aqueous solutions is spontaneous and entropy-driven. The micellization process is enthalpy-entropy compensated with the compensation temperature (Tc) of 308 ± 1 K.

MICELLIZATION STUDIES OF DODECYL BENZENESULFONIC ACID AND ITS INTERACTION WITH POLYVINYLPYRROLIDONE

Dodecyl benzenesulfonic acid(DBSA)surfactant was used in the present study to find the effect of concentrationon its electrical conductance in solution from 293-323 K above and below the critical micelle concentration(CMC).Themicellization parameters i.e.degree of counter ion binding(β),aggregation number(n)and number of counter ion micelle(m)were measured.The interaction of DBSA with polyvinylpyrrolidone(PVP)was also studied at 293 K throughconductance and surface tension measure ments.A number of important parameters i.e.critical aggregation concentration(CAC),Gibb's free energy(△G)and binding ratio(R)were determined and the effect of NaCl on the CAC and polymersaturation point(PSP)was also investigated.

EXTRACTION KINEIICS,MICELLIZATION AND INTERFACIAL CHARACTERISTICS OF A NEW EXTRACTANT SYSTEM

The interfacial kinetics,micellization and interfacial characteristics of the synergetic extrac- tion system,D_2EHPA-H_2RPA-Al^(3+),have been studied.H_2RPA is a single long chain alkyl phosphate.We have found that H_2RPA in the mixed extractant system strongly exhibits the characteristics of micellization and interfacial activity.As the concentration of D_2EHPA in- creases,the micellization and interracial activity of H_2RPA decrease.The interfacial adsorption behaviour of H_2RPA is opposite to that of D_2EHPA.It was proved that the kine- tics of non-micella mixed extraction system was controlled by the chemical reaction at inter- face,and the reaction rate equation was obtained.This non-micella mixed extraction system is expected to be used in the future.

Interaction of antipsychotic drug with novel surfactants: Micellization and binding studies

The interaction of cationic gemini surfactants(alkanediyl-α,ω-bis(alkyl dimethylammonium bromide)) with an antipsychotic drug(chlorpromazine hydrochloride(CPZ)) has been investigated. Various micellar and interfacial parameters have been deliberated by surface tension measurement to report the nature of interactions between drug and novel surfactant mixtures. The behavior of mixed systems, their compositions and activities of components have been analyzed in the light of Rubingh's theory. The results indicate synergism in the binary mixtures.The binding study between CPZ and surfactants has been done by spectroscopic techniques such as UV–visible and fluorescence. The results are discussed in the light of the use of gemini surfactants as promising drug delivery agents for phenothiazine drugs, and hence, improve their bioavailability.

Study on Thermosensitive Micellization of Dextran-g-PNIPAAm in Aqueous Solutions

The thermosensitive micellization of dextran-g-PNIPAAm in aqueous solutions has been investigated by fluorescence spectroscopy, dynamic light scattering and transmission electron microscope. The formed polymeric micelles showed different diameters of about 20 nm or 100 nm, when the solution temperature was below or above the phase transition temperature.

Studies on Micellization of a Polystyrene-b-poly(acrylic acid) Copolymer in Aqueous Media by Pyrene Fluorescence

Pyrene probe and TEM have been employed to investigate the behavior of a polystyrene-b-poly(acrylic acid) (PS-b-PAA) copolymer in aqueous solution. A significant annealing temperature effect on the I1/I3 ratio of pyrene was observed and was interpreted in terms of the morphological change of micellar cores. Annealing at a temperature higher than the glass transition temperature (Tg) of PS leads to densification of the hydrophobic core.

Preparation and Unimolecular-Micellization Behavior of Homopolymer of Surface-Active Monomer AMC14AB

（2-acrylamido） ethyl tetradecyl dimethylammonium bromide （AMC14AB） was polymerized in aqueous solu- tion to form the homopolymer P（AMC14AB）. The physicochemical properties of P（AMC14AB） in aqueous solution were mainly studied with fluorescent probe method, surface tension measurement and conductom- etry. The experimental results show that the aggregation morphology of P（AMC14AB） in aqueous solution is unimolecular micelle as expected. Being different from conventional multimolecular micelle systems, the unimolecular micelle system of P（AMC14AB） not only shows critical micellar concentration （CMC=0）, （i.e. once added to pure water, the surface tension decreases immediately in spite how small the density is）, but also the surface tension stays almost the same with the concentration increasing. That is to say, there is no mutational point on the relationship curve between surface tension and concentration. Furthermore, the unimolecular micelle system of P（AMC14AB） has no Krafft temperature, i.e. at any temperature, so long as it is dissolved in water, the unimolecular micelles will form. Besides this, for the solubilization of hydrophobic organic substances, the unimolecular micelle system of P（AMC14AB） is obviously different from the common multimolecular micelle system, having no turning point on the relationship curve between toluene solubi- lizaion amount and P（AMC14AB） concentration, and the solubilizing ability of the unimolecular-micelle system of P（AMC14AB） for hydrophobic organic substances is much higher than that of the conventional multimolecular micelle solutions of common surfactants, such as centyl trimethyl ammonium bromide.

ESR Studies on the Micellization Behaviors of a Series of Novel Asymmetric Gemini Surfactants

The synthesis of a new series of asymmetric cationic gemini surfactant and the investigation of their micellization behaviors by electronic spin resonance (ESR) as well as the surface tension measurements were reported. 4 Oxo 2,2,6,6 te^tra^me^thyl^pi^pe^ri^dine N oxyl (4 oxo TEMPO) is used as the spin probe. The surfactants studied have the general formula [C n H 2 n +1 N +(CH 3) 2C 6H 12 N +(CH 3) 2C m H 2 m +1 ]Br 2 -, referred to as dimeric n 6 m surfactants, in which n and m are the numbers of carbon atoms in the asymmetric side alkyl chains. From the experimental data, rotational correlation time τ c, surface tension and critical micelle concentration (cmc) values, the physical properties of these new surfactants have preliminarily been evaluated. It is shown that this new series of asymmetric gemini surfactants has interesting micellization behaviors, and they are very different in aggregating tendency from their asymmetric analogues.

Micellization and Gelation of the Double Thermoresponsive ABC-type Triblock Copolymer Synthesized by RAFT

A double thermoresponsive ABC-type triblock copolymer （poly（ethyleneglycol）-block-poly （2-（2-methoxyethoxy）ethyl methacrylate）-block-poly（2-（2-methoxy ethoxy） ethyl methacrylate-co-oligo（ethylene glycol） methyl ether methacrylate, PEG-b-PMEO2MA-b-P（MEO2MA-co-OEGMA）） was designed and synthesized by reversible addition- fragmentation chain transfer polymerization （RAFT）. The ABC-type triblock copolymer endowed a thermal-induced two- step phase transition at 29 and 39 ℃corresponding to the thermosensitive properties of PMEOzMA and P（MEO2MA-co- OEGMA） segments, respectively. The two-step self-assembly of copolymer solutions was studied by UV transmittance measurement, dynamic light scattering （DLS）, transmission electron microscopy （TEM） and so on. The triblock copolymers showed the distinct thermosensitive behavior with respect to transition temperatures, aggregate type and size, which was correlated to the degree of polymerization of thermosensitive blocks and the molar fraction of OEGMA in the P（MEO2MA- co-OEGMA） segments. In addition, micelles could further aggregate to form the hydrogel by the self-associate of PEG chains under the abduction of the concentration and temperature. The transition from sol to gel was investigated by a test tube inverting method and dynamic rheological measurement.

Crystallization induced micellization of poly(p-dioxanone)-block-polyethylene glycol diblock copolymer functionalized with pyrene moiety

Poly（p-dioxanone）-block-polyethylene glycol diblock copolymers functionalized with pyrene moieties（Py-PPDO-b-PEG） at the chain ends of PPDO blocks were synthesized for preparing anisotropic micelles with improved stability.The micellization and crystallization of the copolymers were investigated by nano differential scanning calorimetry（Nano DSC）,transmission electron microscopy（TEM）,UV-vis spectrophotometery,fluorophotometer,and dynamic light scattering（DLS）,respectively.The results indicated that the aggregation of pyrene induced by intermolecular interaction lead to micellization of Py-PPDO-b-PEG at much lower concentrations than those of PPDO-b-PEG copolymers without pyrene moieties.The aggregation of pyrene moieties may also serve as nucleation agent and therefore enhance the crystallization rate of PPDO blocks.Fluorescence measurements by using Nile Red as the fluorescent agent indicated that the micelles of Py-PPDO-b-PEG have high stability and load capacity for hydrophobic molecules.

A robust viscoelastic surfactant tolerating 20% HCl up to 150℃ for oil well stimulation

Viscoelastic surfactants(VES)are often used as viscous diverters in acidizing stimulation to prolong the acid consumption time and maximize zonal coverage of the acid for improving well productivity.However,the ceiling temperature of commercial VES cannot exceed 120℃in practical use because of the poor thermal stability and fragile molecular structure,hindering their implementation in hightemperature oil reservoirs,i.e.,≥150℃.Here we synthesized a novel C22-tailed diamine,N-erucaminopropyl-N,N-dimethylamine(EDPA),and examined comparatively its rheological behavior,assemblies morphology and molecular stability in 20 wt%HCl with a commercial VES,erucyl dimethyl amidopropyl betaine(EDAB).The feasibility of EDPA for acidizing stimulation was assessed by acid etching of carbonate rock with its HCl solution at 150℃.Rheological results showed that the 2.5 wt%EDPA—20 wt%HCl solution maintains stable viscosity of 90 m Pa s at 150℃for 60 min,while that of 2.0 wt%EDAB HCl solution is just 1 m Pa s under identical conditions.1H NMR spectra and cryo-TEM observations revealed that the chemical structure and self-assembled architectures of EDPA remained intact in such context,but the EDAB suffered from degradation due to the hydrolysis of the amide group,accounting for the poor heat-resistance and acid-tolerance.The reaction rate of 2.5 wt%EDPA HCl solution with carbonate rock was one order of magnitude lower than that of 20 wt%HCl solution at 150℃,underpinning the potential of EDPA to be used in the high-temperature reservoirs acidizing.This work improved the thermal tolerance of VES in highly concentrated HCl solution,paving a feasible way for the acidization of high-temperature reservoir environments(~150℃).

Dual ligand-targeted Pluronic P123 polymeric micelles enhance the therapeutic effect of breast cancer with bone metastases

Bone metastasis secondary to breast cancer negatively impacts patient quality of life and survival.The treatment of bone metastases is challenging since many anticancer drugs are not effectively delivered to the bone to exert a therapeutic effect.To improve the treatment efficacy,we developed Pluronic P123(P123)-based polymeric micelles dually decorated with alendronate(ALN)and cancer-specific phage protein DMPGTVLP(DP-8)for targeted drug delivery to breast cancer bone metastases.Doxorubicin(DOX)was selected as the anticancer drug and was encapsulated into the hydrophobic core of the micelles with a high drug loading capacity(3.44%).The DOX-loaded polymeric micelles were spherical,123 nm in diameter on average,and exhibited a narrow size distribution.The in vitro experiments demonstrated that a pH decrease from 7.4 to 5.0 markedly accelerated DOX release.The micelles were well internalized by cultured breast cancer cells and the cell death rate of micelle-treated breast cancer cells was increased compared to that of free DOX-treated cells.Rapid binding of the micelles to hydroxyapatite(HA)microparticles indicated their high affinity for bone.P123-ALN/DP-8@DOX inhibited tumor growth and reduced bone resorption in a 3D cancer bone metastasis model.In vivo experiments using a breast cancer bone metastasis nude model demonstrated increased accumulation of the micelles in the tumor region and considerable antitumor activity with no organ-specific histological damage and minimal systemic toxicity.In conclusion,our study provided strong evidence that these pH-sensitive dual ligand-targeted polymeric micelles may be a successful treatment strategy for breast cancer bone metastasis.

Mass transfer process of peanut protein extracted by bis(2-ethylhexyl)sodium sulfosuccinate reverse micelles

The liquid-liquid extraction method using reverse micelles can simultaneously extract lipid and protein of oilseeds,which have become increasingly popular in recent years.However,there are few studies on mass transfer processes and models,which are helpful to better control the extraction process of oils and proteins.In this paper,mass transfer process of peanut protein extracted by bis(2-ethylhexyl)sodium sulfosuccinate(AOT)/isooctane reverse micelles was investigated.The effects of stirring speed(0,70,140,and 210 r/min),temperature of extraction(30,35,40,45,and 50℃),peanut flour particle size(0.355,0.450,0.600,and 0.900 mm)and solidliquid ratio(0.010,0.0125,0.015,0.0175,and 0.020 g/mL)on extraction rate were examined.The results showed that extraction rate increased with temperature rising,particle size reduction as well as solid-liquid ratio increase respectively,while little effect of stirring speed(P>0.05)was observed.The apparent activation energy of extraction process was calculated as 10.02 kJ/mol and Arrhenius constant(A)was 1.91 by Arrhenius equation.There was a linear relationship between reaction rate constant and the square of the inverse of initial particle radius(1/r_(0)^(2))(P<0.05).This phenomenon and this shrinking core model were anastomosed.In brief,the extraction process was controlled by the diffusion of protein from the virgin zone interface of particle through the reacted zone and it was in line with the first order reaction.Mass transfer kinetics of peanut protein extracted by reverse micelles was established and it was verified by experimental results.The results provide an important theoretical guidance for industrial production of peanut protein separation and purification.

A NEW KIND OF SURFACTANT: LONG-CHAINALKYLTRIPHENYLPHOSPHONIUM——FLUORESCENCE SPECTROSCOPIC STUDY ON THE MICELLIZATION BEHAVIOR OF DODECYLTRIPHENYLPHOSPHONIUM BROMIDE IN AQUEOUS SOLUTION

Aggregation of fluorophore-containing molecules results in an increase of the local concentration of fluorophore and a suitable geometric relation between fluorophores, which leads to the formation of excimer or exciplex. It proved to be of great importance in the investigation of molecular aggregation in solution. Wu et al. have reported the observa-

Synthesis, Micellization and Characterization of Novel Amphiphilic β-Cyclodextrin/Poly（L-aspartate） Copolymer

A novel amphiphilic β-cyclodextrin/poly（L-aspartate）（β-CD-PASP） copolymer was prepared by ringopening polymerization of polysuccinimide（PSI）. This copolymer bears β-CD units along the macromolecular chain and the structure was characterized by infrared（IR） and proton nuclear magnetic resonance（Ill NMR）. The molecular weight of the copolymer was determined by gel permeation chromatography（GPC）. The copolymer micelle were prepared by direct dissolution method. The critical micelle concentration（CMC） of the copolymer micelle was measured by flourescence technique with pyrene as probe. The size distribution of micelle was characterized on a dy- namic laser light scattering particle size analyzer and its shape was observed by transmission electron microscopy（TEM）. The results show that the copolymer could self-assemble into micelle with a low CMC, and the effective diameter of the micelle was 116.3 nm. The methotrexate（MTX）-loaded micelle were prepared and the drug loading content（DLC） was 22.86%. The MTX-loaded cooolvmer exhibited a better water-solubility than the free drug.

Influence of fatty acids in edible oils on lutein micellization and permeation in a simulated digestion model

Lutein is a nutraceutical compound that promotes human eye health and prevents neurodegenerative diseases.The oral bioavailability of lutein is affected by both extrinsic and intrinsic factors in the host.Although hydrophobicity of the compound is further challenging,its lipophilicity can be utilized to micellize and thereby improve its oral bioavailability.Currently,available data on the effects of dietary fats on lutein micellization and permeation is limited and needs further exploration.In this study,the influence of 17 carrier type edible oils on lutein micellization and permeation,was investigated in a simulated digestion model.The overall effectiveness of these oils to permeate micellized lutein was attributed to its Fatty Acid(FA)profile.While 94%of the edible oils exhibited a positive influence on the permeation of micellized lutein,the micellization and permeation efficiency of these oils were significantly(p≤0.05)modulated by the saturation of FA in the order Saturated(SFA)>Mono-Unsaturated(MUFA)>Poly-Unsaturated(PUFA).The highest apparent permeability coefficient was exhibited by lutein micellized in ghee(3.01×10^(-6) cm/s)and butter(2.93×10^(-6) cm/s),which was 1.28 and 1.24 folds higher than lutein alone(2.35×10^(-6) cm/s)respectively.Exceptionally MUFA rich olive oil and PUFA rich flaxseed oil improved lutein permeation by 1.19(2.80×10^(-6) cm/s)and 1.14 folds(2.69×10^(-6) cm/s)respectively.This study is the first to report the influence of saturated fatty acids on micellization and permeation of lutein.Furthermore,the outcomes of this study offer the field of lutein delivery systems a fresh perspective.

In vitro pancreatic lipase,cholesterol esterase and cholesterol micellization inhibitory activity of Sri Lankan low grown orthodox Orange Pekoe grade black tea(Camellia sinensis L.)

Objective:To access the pancreatic lipase,cholesterol esterase and cholesterol micellization inhibitory activities of Sri Lankan low grown orthodox Orange Pekoe grade black tea made from uppermost tender leaves and unopened buds of Camellia sinensis L.Methods:Black tea brew(BTB)was made according to International Organization for Standardization 3103 specifications and concentrations of BTB tested were 37.5,75.0,150.0,300.0 and 600.0μg/mL for antilipase and anti-cholesterol esterase assays and 0.25,0.50 and 1.00μg/mL for cholesterol micellization inhibitory assay.Results:The results showed that BTB of Sri Lankan low grown orthodox Orange Pekoe grade black tea has marked and dose-dependent(r^(2)=0.95)cholesterol micellization inhibitory activity in vitro comparable to epigallocatechin gallate,the reference drug used.In contrast,BTB had only mild but dose-dependent(r^(2)=0.94)inhibitory activity against pancreatic lipase and weak inhibitory effect(up to 13.17%)on pancreatic cholesterol esterase.Conclusions:It is concluded that consumption of BTB of Sri Lankan low grown orthodox Orange Pekoe grade tea as a beverage may be a useful strategy in the management of hyperlipidaemia.

Hydrophobic terminal group of surfactant initiating micellization as revealed by^1H NMR spectroscopy

The critical aggregation concentration（CAC） of four with three kinds of conventional surfactants, namely,two cationic surfactants [hexadecyltrimethyl ammonium bromide（CTAB） and tetradecyltrimethyl ammonium bromide（TTAB）], one anionic surfactant [sodium dodecyl sulfate（SDS）], and a nonionic surfactant [Triton X-100（TX-100）], were determined by variation of ^1H chemical shifts with surfactant concentrations. Results show that the CAC values of protons at different positions of the same molecule are different, and those of the terminal methyl protons are the lowest, respectively, which suggests that the terminal groups of the alkyl chains aggregates first during micellization. Measurement of the transverse relaxation time（T2） of different protons in SDS also show that the terminal methyl protons start to decrease with the increase in concentration first, which supports the above mentioned tendency.

Effect of bovine serum albumin on the micellization of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymers in aqueous solutions by fluorescence spectroscopy

Effect of bovine serum albumin(BSA)on the temperature-dependent association behavior of poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide)(PEO-PPO-PEO)block copolymers was investigated using pyrene fluorescence spectroscopy.The critical micellization temperature(CMT)of pluronics in aqueous solution was increased by the addition of BSA.A closed association model was used to obtain the standard free energies(△DG^(0)),enthalpies(△DH^(0)),and entropies(△DS^(0))of micellization.The standard enthalpy and entropy of micellization for pluronic polymers in water were decreased with an increase of the BSA content.The more PPO component in the pluronic polymer,the higher the changed values of micellization enthalpy and entropy.The hydrophobic part of the pluronics,PPO,was responsible for the interaction between pluronics and BSA.Hydrophobic interaction between PPO and BSA was correlated to the alternation of the PPO-PPO interaction by the addition of BSA,which would shift the CMT toward higher temperature and alter the thermodynamic parameters of micellization for pluronics in aqueous solutions.