Micelle Concentration Of Surfactant Research Articles

Carbon quantum dots as fluorescent probes in the measurement of the critical micelle concentration of surfactants

The critical micelle concentration (CMC) is one main parameter of surfactants, so an accurate, rapid, and convenient method for CMC determination is of great significance for surfactant applications. In this paper, three samples of carbon quantum dots (CQDs) with different fluorescence properties were developed as fluorescent probes for the CMC determination of CTAB, SDS, Triton X-100, perfluoro OBS and Pluronics® P-123. The fluorescence excitation and emission spectra of a constant amount of the CQDs in different concentrations of the surfactant solution were recorded, and then the CMC values of the surfactant were deduced from the fluorescence intensity change and the Stokes shift variation. The obtained CMC data using three samples of the CQDs agree well with those in the published literature. It is also demonstrated that in the micellization process the interaction between the CQDs and the surfactant molecules is complicated, because the fluorescence properties of the CQDs are found to be related to the characteristics of the CQDs, the head group type of ionic surfactants, the chemical structure between the hydrophobic and hydrophilic segment, and the chemical nature of the hydrophobic chains of the surfactants. So, the CQDs are demonstrated to be located at the palisade layer in the surfactant micelles due to the surface-attached polar groups on the CQDs although the CQDs are mainly hydrophobic as fluorescent probes. The fluorescent CQDs are considered to be new choices of the fluorescent probes in the facile CMC measurement of the surfactants.

Synthesis and surface activity of novel amino acid surfactants

AbstractAmino acid surfactants (AASs) based on environmentally friendly biomasses have the characteristics of renewable, easy biodegradation, antibacterial and low toxicity, and have been widely used in daily chemicals, pharmaceuticals, and other fields. This study concerned the use of octanal and amino acids as raw materials. In addition, seven types of amino acid‐based surfactants, through Collins reagents, Wittig‐Hornor reaction, and aza‐Micheal addition reaction, and amino acid head groups were connected with the alkyl chain by the CN bond. The structures were confirmed by infrared spectroscopy (FT‐IR) and nuclear magnetic resonance spectroscopy (1HNMR). Its surface activity and adsorption properties are evaluated. The physical properties of amino acid‐based surfactants were tested by surface tension and dynamic contact angle. The results demonstrated that histidine‐based amino acid surfactant (C8His) has the lowest critical micelle concentration (CMC) and surface tension at CMC (γCMC), 0.39 mmol L−1 and 28.79 mN L−1, respectively. Amino acid residues contribute to reducing the critical micelle concentration of surfactant. The interfacial adsorption of glycine‐based amino acid surfactant (C8Gly) significantly improved with the increase in temperature, so the surface tension decreased significantly. In addition, sodium chloride could effectively enhance the interfacial adsorption, and the gas–liquid interfacial tension and contact angle of AASs decrease.

Role of Polyanions and Surfactant Head Group in the Formation of Polymer-Colloid Nanocontainers.

This study was aimed at the investigation of the supramolecular systems based on cationic surfactants bearing cyclic head groups (imidazolium and pyrrolidinium) and polyanions (polyacrylic acid (PAA) and human serum albumin (HSA)), and factors governing their structural behavior to create functional nanosystems with controlled properties. Research hypothesis. Mixed PE-surfactant complexes based on oppositely charged species are characterized by multifactor behavior strongly affected by the nature of both components. It was expected that the transition from a single surfactant solution to an admixture with PE might provide synergetic effects on structural characteristics and functional activity. To test this assumption, the concentration thresholds of aggregation, dimensional and charge characteristics, and solubilization capacity of amphiphiles in the presence of PEs have been determined by tensiometry, fluorescence and UV-visible spectroscopy, and dynamic and electrophoretic light scattering. The formation of mixed surfactant-PAA aggregates with a hydrodynamic diameter of 100-180 nm has been shown. Polyanion additives led to a decrease in the critical micelle concentration of surfactants by two orders of magnitude (from 1 mM to 0.01 mM). A gradual increase in the zeta potential of HAS-surfactant systems from negative to positive value indicates that the electrostatic mechanism contributes to the binding of components. Additionally, 3D and conventional fluorescence spectroscopy showed that imidazolium surfactant had little effect on HSA conformation, and component binding occurs due to hydrogen bonding and Van der Waals interactions through the tryptophan amino acid residue of the protein. Surfactant-polyanion nanostructures improve the solubility of lipophilic medicines such as Warfarin, Amphotericin B, and Meloxicam. Surfactant-PE composition demonstrated beneficial solubilization activity and can be recommended for the construction of nanocontainers for hydrophobic drugs, with their efficacy tuned by the variation in surfactant head group and the nature of polyanions.

Glassy and compressed nanoemulsions stabilized with sodium dodecyl sulfate in the presence of poly(ethylene glycol)-diacrylate.

The rheology of concentrated nanoemulsions is critical for their formulation in various applications, such as pharmaceuticals, foods, cosmetics, and templating advanced materials. The rheological properties of nanoemulsions depend on interdroplet interactions, Laplace pressure, dispersed phase volume fraction, and continuous phase properties. The interdroplet forces can be tuned by background electrolytes (i.e., charge screening), surfactant type, the excess surfactant micelle concentration, and depletant molecules such as polymer chains. In the current research, we study the effect of varying the content of poly(ethylene glycol)-diacrylate (PEGDA) on the interfacial tension of the water-oil phase and rheological properties of concentrated nanoemulsions with 50% and 60% volume fractions. Sodium dodecyl sulfate (SDS) is used as the ionic surfactant. The final concentrated nanoemulsions are repulsive according to overall interaction potentials and are in the glass and compressed states based on the effective volume fraction estimation. They contain nearly same SDS concentration on the droplet surface and also in the bulk, but a different amount of PEGDA. The scaled rheological properties of the glassy nanoemulsions show a higher dependency on the PEGDA content and the possible effect of polymer-surfactant complexations compared to those of the compressed ones. This dependency is more pronounced in small strain amplitudes but not in large strains in the non-linear regime. These results provide insights into formulating concentrated nanoemulsions with controlled rheology for expanded application areas.

Synthesis of Highly Conductive Poly(3-hexylthiophene) by Chemical Oxidative Polymerization Using Surfactant Templates.

Poly(3-hexylthiophene) (P3HT) was systematically synthesized by chemical oxidative polymerization in chloroform with ferric chloride (FeCl3) as the oxidizing agent and various surfactants of the shape templates. The effects of 3HT: FeCl3 mole ratios, polymerization times, and surfactant types and concentrations on the electrical conductivity, particle shape and size were systematically investigated. Furthermore, dodecylbenzenesulfonic acid (DBSA), p-toluenesulfonic acid (PTSA), sodium dodecyl sulfate (SDS), and sodium dioctyl sulfosuccinate (AOT) were utilized as the surfactant templates. The P3HT synthesized with DBSA at 6 CMC, where CMC stands for the Critical Micelle Concentration of surfactant, provided a higher electrical conductivity than those with PTSA, SDS and AOT. The highest electrical conductivity of P3HT using DBSA was 16.21 ± 1.55 S cm−1 in which the P3HT particle shape was spherical with an average size of 1530 ± 227 nm. The thermal analysis indicated that the P3HT synthesized with the surfactants yielded higher stability and char yields than that of P3HT without. The P3HT_DBSA electrical conductivity was further enhanced by de-doping and doping with HClO4. At the 10:1 doping mole ratio, the electrical conductivity of dP3HT_DBSA increased by one order of magnitude relative to P3HT_DBSA prior to the de-doping. The highest electrical conductivity of dP3HT_DBSA obtained was 172 ± 5.21 S cm−1 which is the highest value relative to previously reported.

Surfactant based nanoreactor micellar assembly: An innovative route for synthesis of 2-thioxo-2,3-dihydroquinazolin-4(1H)-ones

• Synthesis of an efficient surfactant, 4-(dimethylamino)-1-hexadecylpyridinium hydroxide [DAHP] + [OH]-. • A novel route for the synthesis of 2-thioxo-2,3-dihydroquinazolin-4(1 H )- ones. • The micelle size by SAXS found to be 14.8 nm (diameter) and 2.6 nm (the spacing between two micelles). • High yield, water as a solvent, short reaction time, easy separation of products are remarkable properties. We described an innovative route for synthesis of 2-thioxo-2,3-dihydroquinazolin-4(1 H )-ones using isatoic anhydride and phenyl isothiocyanate via in situ formation of anthranilic acid. The reaction was performed in the nano-micellar assembly of surfactant, 4-(dimethylamino)-1-hexadecylpyridinium hydroxide [DAHP] + [OH] - as a nano-reactor. The micelle concentration of surfactant is found to be 0.002 mol.dm −3 using the conductivity data. The micellar particle dimensions were demonstrated from small-angle X-ray scattering (SAXS) analysis viz. micelle diameter and the interspacing between two micelles which were found to be 14.8 nm and 2.6 nm, respectively. From the TGA analysis, the surfactant is thermally stable up to 250 °C with 76.01 % weight loss. The practical simplicity, atom economy, good to high yields, ease of product isolation and purification, water as eco-benign solvent and catalyst recyclability are the remarkable aspects of the present methodology.

Physicochemical and electrochemical methods for determination of critical micelle concentrations of surfactants: a comprehensive review

Physicochemical and electrochemical methods for determination of critical micelle concentrations of surfactants: a comprehensive review

Dual emissive amphiphilic carbon dots as ratiometric fluorescent probes for the determination of critical micelle concentration of surfactants.

The sensitive determination of the critical micelle concentration (CMC) of surfactants is very important for their practical application. Due to their good sensitivity and simple operation, pyrene and its derivatives have been widely used as fluorescent probes to detect the CMC. However, their virulent and poor water-soluble nature has limited their wide employment. In the present work, environmentally friendly amphiphilic carbon dots (Cdots) with dual-color emission and absolute quantum yield (PLQY) values higher than 50% have been fabricated through a solvothermal process, which could successfully serve as self-calibrative, ratiometric fluorescent probes to estimate the CMC of both non-ionic and ionic surfactants. This work not only provides a new strategy to design green ratiometric fluorescent probes for the CMC measurement of surfactants but also expands the application of Cdots in the colloidal field.

Surfactant Adsorption to Different Fluid Interfaces

Surfactant adsorption to fluid interfaces is ubiquitous in biological systems, industrial applications, and scientific fields. Herein, we unravel the impact of the hydrophobic phase (air and oil) and the role of oil polarity on the adsorption of surfactants to fluid interfaces. We investigated the adsorption of anionic (sodium dodecyl sulfate), cationic (dodecyltrimethylammonium bromide), and non-ionic (polyoxyethylene-(23)-monododecyl ether) surfactants at different interfaces, including air and oils, with a wide range of polarities. The surfactant-induced interfacial tension decrease, called the interfacial pressure, correlates linearly with the initial interfacial tension of the clean oil-water interface and describes the experimental results of over 30 studies from the literature. The higher interfacial competition of surfactant and polar oil molecules caused the number of adsorbed molecules at the interface to drop. Further, we found that the critical micelle concentration of surfactants in water correlates to the solubility of the oil molecules in water. Hence, the nature of the oil affects the adsorption behavior and equilibrium state of the surfactant at fluid interfaces. These results broaden our understanding and enable better predictability of the interactions of surfactants with hydrophobic phases, which is essential for emulsion, foam, and capsule formation, pharmaceutical commodities, cosmetics, and many food products.

Multi-sensing response, molecular docking, and anticancer activity of donor–acceptor chalcone containing phenanthrene and thiophene moieties

Donor–Acceptor (D–π–A) chalcone containing phenanthrene and keto-thiophenly moieties, abbreviated as PhTPO, was synthesized and characterized. The solvatochromic effect was investigated in different solvents of various polarities. The absorption and fluorescence spectra have shown bathochromic shifts from non-polar to polar solvents due to intramolecular charge transfer interactions. The fluorescence characteristics (fluorescence intensity, fluorescence maxima, and energy) of PhTPO are highly sensitive to the polarity of the solvents compared to the corresponding absorption spectra. In addition, the inclusion characteristic of PhTPO in different organized assemblies was studied. The spectral changes suggested that PhTPO would be useful to study the microenviromental polarity and evaluation of critical micelle concentrations of the studied surfactants. Reversible acidochromic behavior was observed after addition of H2SO4/NaOH with a significant color change. Further, the optical sensing response towards H+, Co2+, Ni2+, Pb2+ and Cd2+ ions was investigated. Also, it responds well to the tested metal ions as reflected from the changes in both the absorption and emission spectra upon adding different concentrations of the metal salts. The solid complexes of PhTPO with Co2+, Ni2+, Pb2+ and Cd2+ were then synthesized and characterized. Depending on the magnetic moments results, the geometric structures were found to be octahedral and tetrahedral for paramagnetic Co2+, and Ni2+ complexes, respectively, while they are diamagnetic for Pb2+ and Cd2+ complexes. Moreover, the geometry of PhTPO and its complexes were confirmed by the density functional theory (DFT) using DMOL3 program. The binding affinity towards the epidermal growth factor receptor (EGFR) protein was also investigated by the Molecular Operating Environment (MOE) software. The anticancer activity was then evaluated against four different cell lines using MTT assay. The results suggest that the investigated PhTPO would be potential candidate for solvents polarity sensors, as a probe to characterize critical micelle concentrations of surfactants, and sensor for the studied metal ions and H+ proton. In addition, [PhTPONi2+] and [PhTPOCo2+] complexes are good candidate for further antitumor activities studies owing to their potent cytotoxic and anticancer activities compared to the Pb2+ and Cd2+ complexes.

Evaluation of Non‐Ambiguous Critical Micelle Concentration of Surfactants in Relation to Solution Behaviors of Pure and Mixed Surfactant Systems: A Physicochemical Documentary and Analysis

AbstractCritical micelle concentration (CMC) is a fundamental physical parameter of surfactant aggregation in solution. The CMC is determined by different methods, tensiometry, conductometry, microcalorimetry, fluorimetry, and so on. However, it is known that though CMC is reported as a single value, in reality, micelle formation occurs over a narrow range of concentration for different experimental procedures produce different results. We shall discuss about a unique procedure of measuring correct CMC applicable to all potential methods used in practice. This is essential for the evaluation of thermodynamic properties of the micelle forming process in pure and mixed states in terms of solution theories. As we in this short documentary want to deal with various aspects of Milton Rosen's research—wherein we have also worked—a few other facets of surfactant chemistry research, besides the micelle formation, are also briefly discussed. In mixed surfactant systems, synergistic effects in various surfactant properties like detergency, foaming, solubilization, and so on are found whereas in some others non‐synergistic effects are observed. Dehydration of micelles with an increase in temperature or by the addition of hydrophilic substances may cause clouding to the system. Soluble amphiphilic systems produce Gibbs monolayer at the air/water interface; insoluble amphiphiles form Langmuir monolayers. A documentary of the above aspects will be herein presented and discussed. We mention that this article is neither an original research article nor a review article. This is a mixture of the two: a documentary of both original research and some review of our works presented in memory of Prof. Milton Rosen.

Solubilization of reactive dyes by mixed micellar system: Synergistic effect of nonionic surfactant on solubilizing power of cationic surfactant

In this manuscript solubilization of reactive dyes i.e. Reactive red 195 and reactive blue 221, by simple and mixed micellar solution, is being reported using UV/visible spectroscopy and electrical conductivity. UV/visible spectroscopy has been used to have quantitative measurement of degree of solubilization in term of partition coefficient (Kx) and Gibbs energy of partition (ΔGp) while electrical conductivity has been employed to detect critical micelle concentration of surfactants and, accordingly, to calculate thermodynamic parameters. It has been concluded that solubilization is exothermic, spontaneous and enthalpy driven process. The partitioning and binding of RB-195 has been found to be more favorable and spontaneous than that of RB-221. The results clearly indicate that the inclusion of TX-100 in micellar media of CTAB has significantly enhanced its solubilizing power.

Determination of the critical micelle concentration by absorbance and fluorescence techniques using fluorescein probe

We reported a unique and sensitive probe (fluorescein) for determination the critical micelle concentration(CMC) of ionic surfactants based on both fluorescence and absorbance properties of probe in micellar solution. We found that the spectral properties (fluorescence and absorbance) of fluorescein are affected by different types of surfactants. For this purpose spectrophotometric technique using fluorescein as probe to determine the critical micelle concentration of cationic, anionic and zwitterionic surfactants. The critical micelle concentrations of surfactants were determined from the sigmoidal shaped plots or inflection points. The obtained CMC values were in good agreement with the values obtained with conductivity measurements or with literature values.

Scaling of binding affinities and cooperativities of surfactants on carbon nanotubes

High-end applications of single-walled carbon nanotube (SWNT) require detailed understanding of their binding affinity (Kd) with surfactants. Here, we quantitatively determined the comprehensive Kd and aggregation number (γ) of nine nonionic and anionic surfactants according to SWNT chirality. Photoluminescence (PL)-based titration using flavin mononucleotide (FMN)-SWNT complexes showing the largest redshifted optical transition enabled quantitative comparison of the surfactants and displayed distinct first and second regimes which correspond to partial and full replacements of FMN, respectively. Especially, the second transition exhibited sigmoidal PL change whose middle point denoted by the inverse of Kd slightly differs from critical micelle concentration of surfactant alone, depending on its functional groups. Moreover, nonionic surfactants displayed larger Kd and lower γ values than the anionic did. Specifically, Kd values between Pluronic F108 and sodium dodecyl sulfonate differ by four orders of magnitude. Such differences were rationalized in terms of the occupied volume of the micelle based on the hydrodynamic volume and γ. During the replacement, Kd and γ were affected by the degree of surfactant rearrangement induced by aging process, leading to more stable complex. Scaling the interactions between surfactant and SWNT provides useful guidelines to design novel SWNT sorting method using more than two surfactants.

Evaluation of a sulfanilic acid based surfactant in crude oil demulsification: an experimental study

In this study, 2-Amino-5-Dodecyl Benzene Sulfonic Acid (ADBSA) surfactant has been prepared and tested as crude oil emulsions demulsifier. Electrical conductivity method was used to obtain the critical micelle concentration of surfactant. A critical micelle concentration value of 0.225 wt.%. Bottle testing measurements were conducted to investigate the effect of several parameters including temperature, water content, salinity, demulsifier dosage and type of crude oil (composition) on the demulsification efficiency in presence of new synthetic demulsifier. A reduction of emulsion stability was observed with increasing water content or demulsifier dosage decrease. A water separation index of 98% was recorded at 60 °C.

Determination of Critical Micelle Concentration of Surfactants by Headspace Gas Chromatography

AbstractThis paper presents a new method for the determination of the critical micelle concentration (CMC) of surfactants in water at elevated temperatures using headspace gas chromatography (HS‐GC). A volatile compound (e.g., toluene) was spiked into the studied solution. At a given temperature, the concentration of volatile species in the vapor phase (measured by HS‐GC) is proportional to the surfactant concentration in the liquid phase in a closed vial. This tendency will change after the solution is saturated with surfactant. By plotting the GC signal of the vapor species vs the concentration of the surfactant concentration in the solution, a breakpoint, i.e., corresponding to the CMC of the surfactant. The present method has good precision (RSD < 10%) and good accuracy. It is also very simple and can be used as an automated method for determining the critical micelle concentration of surfactants at the temperature of interest.

SURFACTANT INDUCED INTERFACIAL ANCHORING TRANSITIONS IN NEMATIC LIQUID CRYSTAL DROPLETS ON GLASS SURFACES

The interfacial adsorption of surfactants at planar nematic liquid crystal (NLC)–water interface induces an ordering transition from a tilted to perpendicular anchoring with the increase in surfactant concentration at [Formula: see text], where [Formula: see text] is the Critical Micelle Concentration of surfactants in water. In this study, we show that depending upon the surfactant structure a tilted to perpendicular NLC anchoring transition is observed at [Formula: see text] in 5CB droplets of size 50–70[Formula: see text][Formula: see text]m. Micrometer sized 5CB droplets are deposited on glass surfaces using flow coating of 5CB-in-ethanol solutions. When placed on 5CB drop decorated glass surfaces, the aqueous surfactant solutions of aliphatic chain surfactants (SDS, CTAB and CPBr) at [Formula: see text], result in an optical transition to a bright-cross texture attributed to the tilted anchoring of 5CB molecules at 5CB–water interface. At [Formula: see text], perpendicular anchoring of 5CB molecules at 5CB–water interface results in a droplet texture with a hedgehog defect. In contrast, aqueous solutions of SDBS lead to 5CB droplets with a bright-cross texture regardless of the surfactant concentration in the aqueous phase. These results indicate that the orientation of 5CB molecules is independent of the nature of the surfactant headgroup. In addition, 5CB droplet decorated OTS treated glass substrates show a hedgehog texture which disappears completely on exposure to organic vapors with the response time-dependent on the polarity of the vapor molecules.

Determination and calculation of micro-structural parameters of SDS/BA/H2O micelle

The micro-structural characteristics of sodium dodecyl sulfate (SDS)/benzyl alcohol (BA)/H2O micelle were studied by the methods of theoretical calculation, viscosity, dynamic light scattering, and Raman spectra. The radius of the spherical micelle was about 22.86–35.85 nm. The maximum length of rod-like micelle could reach up to 250.95 nm. In the micelle, the carbon chain of SDS was not completely stretched but still bended. The total chain length of SDS molecule in the micelle appeared to be 2 nm approximately. Both the axis ratio and the shape factor of rod-like micelles increased with the increase of aggregation number. The intrinsic viscosity and relative viscosity of spherical micelles were less than those of the rod-like micelles. The relative viscosity and critical micelle concentration values decreased gradually with the increase of BA content. The second critical micelle concentration of surfactant could also be determined through viscosity method.

Influence of the hydrophilic head size and hydrophobic tail length of surfactants on the ability of micelles to stabilize citral.

Surfactant-made micelles can control the rate of chemical degradation of poorly water-soluble food flavors. To evaluate how the molecular structure of surfactant has an influence on the chemical decomposition rate of citral, micelles were prepared with polyoxyethylene alkyl ether-type surfactants that had similar molecular structures but various hydrophilic head sizes and hydrophobic tail lengths. At a critical 20× micelle concentration of surfactant, there was no significant difference in the chemical degradation rate of citral in micelles in neutral pH, regardless of the hydrophilic head size or hydrophobic tail length. In an acidic environment, the degradation rate constant of citral generally increased proportionally with increasing hydrophilic head size of surfactant (0.1563 and 0.2217 for surfactants with 23 and 100 oxyethylene units, respectively) but the length of hydrophobic tail did not affect the citral stability. Also, little difference (0.2217 and 0.2265 for surfactant having 100 oxyethylene units with and without Fe(3+) ) in degradation rate constant of citral between simple micellar solution and micellar solution containing iron suggested that iron ions could not accelerate citral degradation in micelles, regardless of the form of iron (Fe(2+) and Fe(3+) ). This work concludes that although the concentration of surfactant could be relevant, if its concentration could be controlled in the same manner as the critical micelle concentration, then a polyethylene alkyl ether-type surfactant with a small hydrophilic head could more efficiently stabilize citral at an acidic pH. © 2015 Society of Chemical Industry.

Wetting and adsorption properties of n-octyl-β-d-glucopyranoside and monorhamnolipid in the system polytetrafluoroethylene–solution–air

Abstract The measurements of the contact angle of the aqueous solutions of n -octyl-β- d -glucopyranoside (OGP) and monorhamnolipid (RL) on polytetrafluoroethylene surface (PTFE) as well as the water, diiodomethane and formamide on the PTFE covered by the OGP and RL layer were made at 293 K. On the basis of the obtained contact angle the values of the critical surface tension of the PTFE wetting, adhesion work of the solutions to the PTFE and the adsorption of the OGP and RL at the PTFE–water interface were calculated. The tendency of OGP and RL to adsorb at the PTFE–water interface was considered by determination of the standard Gibbs free energy of adsorption of these surfactants. To determine this energy, a new equation was proposed which was based on the critical micelle concentration of surfactants (CMC), surface tension and contact angle of solution at the CMC. The values of the standard Gibbs free energy of OGP and RL adsorption were compared to those determined by using the Langmuir and Gu and Zhu equations. It was stated that there is the good agreement between these values calculated in different ways. These values are close to those determined for the OGP and RL at the water–air interface.