Aggregation,Counter Ion Binding and Adsorption Behaviors of Cetylpyridinium Chloride in Water/Glycerol Media at 25 °C

The critical micelle concentrations (CMC) of cetylpyridinium chloride (CPC) in water/glycerol media and in the presence of sodium chloride were determined at 25 °C by surface tension and conductance methods. Variation in CMC follows the normal trend, i.e., it increases with increases in glycerol content and decreases on adding NaCl. Empirical analysis of the exponential increase in CMC of CPC with weight per cent of glycerol is indicative of CMC having two components; one component being dependent while the other independent of the glycerol amount. The counter ion binding constant was determined from both slope–ratio and Corrin-Harkins methods and showed no dependence on glycerol amount, thus confirming the unusual trend in the behavior of β in water/glycerol media. In a water/glycerol medium, the ratio of solvent surface tension to limiting surface tension at CMC is also independent of the glycerol amount, whereas the Gordon Parameter decreases with increasing glycerol content as in other aqueous organic solvents. The air–solution interface becomes saturated by the adsorption of CPC when the concentration of added NaCl is about 0.02 mol kg⁻¹ irrespective of the glycerol amount.     

Mixed Micellization of Sodium Dodecylbenzene Sulfonate with Polyoxyethylene Lauryl Ether Surfactants (POLE4 and POLE23) in n-Butanol Aqueous Solution

The values of critical micelle concentration and counterion binding constant for the mixed micellizations of sodium dodecylbenzenesulfonate (DBS) with polyoxyethylene(4) lauryl ether (POLE4) and polyoxyethylene(23) lauryl ether (POLE23) in aqueous solution of n-butanol at 25 °C were determined as a function of the overall mole fraction of DBS by using the electric conductivity and the surface tension methods. Various thermodynamic parameters were calculated and analyzed for the mixed micellization of DBS/POLE4 and DBS/POLE23 systems by means of the equations derived from the nonideal mixed micellar model. The results show that DBS/POLE23 mixed system has a greater deviation from the ideal model than DBS/POLE4 mixed system. These deviations of thermodynamic parameters for both mixed systems become greater with the addition and concentration increase of n-butanol.     

Effect of Benzheterazoles on the Micellar Behavior of Sodium Dodecylsulfate in Dimethylsulfoxide: A Conductometric and Spectroscopic Approach

In this article, we report intermolecular interactions in terms of the effect of benzfused heterocyclic compounds, i.e., 2-thioureidobenzimidazole and 2-thioureidobenzoxazole (0.00, 0.01, and 0.05 mol kg⁻¹), on the micellization behavior of sodium dodecylsulphate (SDS) (1–52 mmol kg⁻¹) in dimethylsulphoxide (DMSO) at different temperatures (293.15–313.15 K) through conductometric and spectroscopic investigations. The variation of specific conductance with SDS concentration has been utilized to estimate the critical micelle concentration ( CMC). The above-performed techniques infer that the presence of additives results in a decrease in the CMC values. Various standard thermodynamic parameters such as free energy change (), enthalpy change (), and entropy change () of micellization have been determined using the temperature dependence of CMC. The above calculated parameters and also UV–visible and fluorescence spectroscopy have been used to obtain information regarding the various interactions between the compounds and surfactant aggregates. In addition, an attempt has also been made to examine the minimum inhibitory concentration (MIC) of the heterocompounds, which indicates the effectiveness of these compounds against fungus growth at a particular concentration. These synthetic heterocyclic compounds find increasing applications in material science, medicinal chemistry, and biochemistry due to their antifungal and antioxidant properties.     

Mixed Micellization and Mixed Monolayer Formation of Sodium Cholate and Sodium Deoxycholate in Presence of Hydrophobic Salts Under Physiological Conditions

Mixed micellization and mixed monolayer formation of two bile salts namely sodium cholate (NaC) and sodium deoxycholate (NaDC), in the presence of sodium chloride (NaCl) and three hydrophobic salts including sodium acetate (NaAc), sodium butanoate (NaBu) and sodium hexanoate (NaHx) in 10 mM phosphate buffer (pH 6.5) at 37 °C were investigated by means of surface tension measurements. The experimental results were utilized to evaluate various parameters like critical micellar concentration (CMC), micellar and monolayer interaction parameter (β and β ^σ), micellar and monolayer mole fractions (X and Z), activity coefficients of two bile salts in mixed micelles and monolayer (f and f _(σ)), surface excess (Γ_max) and minimum surface area per molecule of bile salt (A _min). Mixed micelles and mixed monolayer were found to show slight non-ideality and both these phenomena have been found to be affected differently in the presence of various additive salts with NaHx showing larger effects. Higher efficiency of NaHx in affecting both phenomena has been attributed to its appreciable hydrophobicity and surface activity, thus showing stronger interactions with bile salt molecules.     

Counter-ion Effect on Micellization of Ionic Surfactants: A Comprehensive Understanding with Two Representatives, Sodium Dodecyl Sulfate (SDS) and Dodecyltrimethylammonium Bromide (DTAB)

Various micelle parameters viz., critical micelle concentration (CMC), counter-ion binding (β), aggregation number (N), hydrodynamic radius (R _h), micelle zeta potential (ζ) and energetic parameters, free energy of micellization ( $ \Updelta G_{\text{m}}^{0} $ ), enthalpy of micellization ( $ \Updelta H_{\text{m}}^{0} $ ) and entropy of micelle formation ( $ \Updelta S_{\text{m}}^{0} $ ) were determined for sodium dodecylsulfate, and dodecyltrimethylammonium bromide in the presence of NaCl for the former and NaBr for the latter. Conductometry and calorimetry methods were used for the measurements of CMC and energetic parameters. The fluorimetric (static quenching) method was employed to determine N and dynamic light scattering to estimate R _h and ζ. The conductometrically determined β was verified from the CMC values by calorimetry using the Corrin–Harkins equation. The results found for the two surfactants of identical tails but different head groups have been presented and discussed. A detailed report on the salt effect using salts containing counter-ions the same as those in the surfactant is found only limitedly in the literature.     

A Systematic Study of Mixed Surfactant Solutions of a Cationic Ester-Bonded Dimeric Surfactant with Cationic, Anionic and Nonionic Monomeric Surfactants in Aqueous Media

A novel cationic biodegradable dimeric (gemini) surfactant, ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride (16-E2-16), containing an ester-linked spacer was synthesized. Its pure and mixed micellization properties with monomeric surfactants cetyl trimethyl ammonium chloride, cetyl pyridinium chloride, sodium dodecyl sulfate, sodium dodecyl benzene sulfonate, cetyl alcohol ethoxylate (20EO) and tert-octylphenol ethoxylate (9.5EO) were investigated by surface tension measurements at 30 °C. The critical micelle concentration (CMC) of 16-E2-16 is well below that of cetyl trimethyl ammonium chloride containing the same number of carbon atoms in the hydrophobic tail per polar head. At different mole fractions of the gemini surfactant, the CMCs of the gemini-conventional binary mixtures were determined and were found to be less than the ideal CMC values in all the cases indicating synergistic interactions. Aggregation number and Stern–Volmer constant, obtained by the fluorescence quenching technique, also support the synergistic behavior of the surfactant systems.     

Aggregation Behavior of Sodium Dodecyl Sulfate and Cetyltrimethylammonium Bromide Mixtures in Aqueous/Chitosan Solution at Various Temperatures: An Experimental and Theoretical Approach

A conductometric study of the mixed micellization behavior between cetyltrimethylammonium bromide (CTAB, a cationic surfactant) and sodium dodecyl sulfate (SDS, an anionic surfactant) was carried out in the absence/presence of various percentages of chitosan in the temperature range of 298.15–318.15 K. The deviations of critical micelle concentration (cmc) from the ideal values indicate the interaction between CTAB and SDS. The micellar mole fraction values according to different proposed models X₁^Rub (Rubingh), X₁^M (Motomura), X₁^Rod (Rodenas), and X₁^id (ideal mole fraction) were estimated and the results obtained reveal the high contribution of CTAB in the mixed micellization, which enhances with the increase of the mole fraction of CTAB. The negative magnitudes of indicate the spontaneous formation of mixed micelles between CTAB and SDS. The values of activity coefficients (f₁ and f₂) were less than unity and the values of the interaction parameter (β) are negative in all cases, which indicate the attractive interaction between CTAB and SDS. The negative values of excess free energy of micellization (ΔG_ex) signify the stability of the mixed micelles. The negative values of in the chitosan systems indicate that micellization is exothermic. The values of were found to be positive in all cases.     

Surface Chemical Properties and Micellization of Disodium Hexadecyl Diphenyl Ether Disulfonate in Aqueous Solution

The surface tension of disodium hexadecyl diphenyl ether disulfonate (C₁₆‐MADS) was measured at different NaCl concentrations (0.00–0.50 mol L^?1) and temperatures (298.0–318.0 K) using the drop‐volume method. The results show that, with increasing temperature, the critical micelle concentration (CMC) of C₁₆‐MADS increases slightly, but the maximum surface adsorption capacity (Γ_max) at the air–water interface decreases. When the concentration of NaCl was increased from 0.00 to 0.50 mol L^?1, the CMC of C₁₆‐MADS decreased from 1.45 × 10^?4 to 4.10 × 10^?5 mol L^?1, but the surface tension at the CMC (γ_cmc) was not affected. When the concentration of NaCl was increased at 298.0 and 303.0 K, the Γ_max of C₁₆‐MADS increased. When the temperature was increased from 308.0 to 318.0 K, the surface excess concentration (Γ_max) of C₁₆‐MADS abnormally decreased from 2.26 to 1.41 μmol m^?2 with increasing NaCl concentration. The micellization free energy () decreased from ?63.98 to ?76.20 kJ mol^?1 with increase of temperature and NaCl concentration. The micellar aggregation number (N_m) of disodium hexadecyl diphenyl ether disulfonate (C₁₆‐MADS) was determined using the molecule fluorescence probe method with pyrene as probe and benzophenone as quencher. The results show that an appropriate N_m could be measured only at surfactant concentration above the CMC. The N_m increased with an increase in C₁₆‐MADS concentration, but the micropolarity in the micelle nucleus decreased. The temperature had little effect on N_m. Compared with typical single hydrophilic headgroup surfactants, aggregates of C₁₆‐MADS exhibit different properties.     

The Effect of Polar Head and Chain Length on the Physicochemical Properties of Micellization and Adsorption of Amino Alcohol-Based Surfactants

In this work, we have synthesized a series of quaternary ammonium from amino alcohols and n-bromoalkanes. The compounds are referred to as C_nEtOH, C_nPrOH, and C_niPrOH (where n = 12 and 14 carbons, EtOH = ethanol, PrOH = propanol, iPrOH = iso-propanol). Their structures were checked using the usual spectroscopic methods [¹H, ¹³C nuclear magnetic resonance (NMR) and infrared (IR)]. Their physicochemical properties in aqueous solution were studied using conductivity, surface tension, and ultra violet (UV)–visible absorption spectroscopy measurements. This study was conducted to show the effect of the linear hydrophobic chain and the location of the OH polar group with respect to the N⁺ quaternary ammonium on the physicochemical properties of the surfactants. The comparison between the physicochemical properties of the surfactants studied shows a distinct effect of the position of the OH group on the critical micelle concentration (CMC), the ionization degree (α), the area occupied at the interface (A_min), the free energy of adsorption (), and the free energy of micellization (). The intermolecular interaction between the synthetic surfactants and the methyl orange (OM) dye is related to the degree of hydration of the micelle, proven by the hypsochromic displacement of OM wavelength (λ_max) and ionization (α) of the micelles. The CMC, the degree of ionization, and the degree of hydration of the micelle follow the same trend.     

烷基二苄醚双季铵盐的合成及在水溶液中的聚集行为

以长碳链溴代烷、N,N-二甲基乙醇胺和对二溴苄为原料,合成了3种不同疏水链长的烷基二苄醚双季铵盐Gemini表面活性剂(10-B-10,12-B-12,14-B-14),采用FTIR、1HNMR和ESI-MS对其结构进行了表征。采用稳态荧光法测定了3种表面活性剂的临界胶束浓度(CMC)和胶束聚集数。结果表明,采用荧光法测定的CMC与表面张力法所得的值基本一致,随着疏水链长从10增加至14,CMC从3.24 mmol/L降至0.056 mmol/L。采用外推法得到3种表面活性剂的临界胶束聚集数(N m)分别为6.98(10-B-10),3.87(12-B-12)和1.62(14-B-14)。动态光散射结果表明,该类表面活性剂在CMC以上易生成囊泡,盐的加入会诱导囊泡转变成胶束。     

Surface and Aggregation Properties of Synthesized Cetyl Alcohol Based Bis-Sulfosuccinate Gemini Surfactants in Aqueous Solution

A series of cetyl alcohol based anionic bis‐sulfosuccinate gemini surfactants (BSGSCA1,4; BSGSCA1,6 and BSGSCA1,8) with different spacer lengths was prepared using dibromoalkanes. The surfactant structure was elucidated using elemental analysis, Fourier transform infrared spectroscopy (FT‐IR) and nuclear magnetic resonance spectroscopy (NMR). Surface tension measurements were used to determine the critical micelle concentration (CMC), the surface tension at the CMC (γ_CMC), surface pressure at the CMC (π_CMC) and efficiency of adsorption (pC20). On the basis of surface studies, the CMC and γ_CMC decreases with increasing length of the spacer group. The micelle aggregation number, determined by fluorescence quenching studies, increases with increasing surfactant concentration above the CMC. The micropolarity in the micelle increases with increasing length of the spacer and decreases with increasing surfactant concentration.     

Aggregation Behavior of Perfluorononanoic Acid/Sodium Dodecyl Sulfate Mixtures

The mixed system of an anionic hydrocarbon surfactant, sodium dodecyl sulfate, and a perfluorinated surfactant, perfluorononanoic acid (PFNA), was investigated by a combination of methods. The critical micellar concentrations (CMC) were determined over a wide range of sample compositions by surface tension, conductivity and UV–visible spectrophotometry using N-(4-nitrophenyl)perfluorononanamide as a molecular probe. The values of CMC obtained by different techniques were in good agreement. In addition, the aggregation numbers were determined in the mixtures with a low content of hydrocarbon surfactant, by measuring the fluorescence quenching of pyrene. The hydrodynamic radii of the aggregates were estimated through the diffusion ordered ¹⁹F- and ¹H-NMR spectroscopy. The values obtained are in agreement with those expected according to the measured aggregation numbers. The analysis of the data with different aggregation models suggests the formation of a non-ideal mixed micelle that is enriched in the perfluorinated surfactant when its mole fraction increases, and that is practically formed by PFNA only at mole fractions higher than 0.8.     

Micellization Studies of Dicationic Gemini Surfactants (m-2-m Type) in the Presence of Various Counter- and Co-Ions

Salts have the ability to influence the water activity and self-association of ionic micelles. In the present case, gemini surfactants; ethanediyl-α,ω-bis(dimethyl alkyl ammonium bromide) (referred to as m-2-m, m = 10, 12, 14) are synthesized and their micellization study in aqueous medium in presence of monovalent inorganic (NaBr, NaNO₃, NaCl, KCl, LiCl) and organic salts (NaTos, NaBenz, NaSal) at 303 K is systematically investigated by conductometric and tensiometric methods. All the salts have the tendency to lower the critical micelle concentration of the surfactants. The effect of inorganic salts on the micellization properties has been found to obey the Hofmeister series. Organic salts reduce the CMC more effectively as compared to inorganic salts. The theoretical models of Rubingh and Rosen have been used to compare the results and obtain the interaction parameters, minimum area per molecule, surface excess, mixed micelle composition, activity coefficients and free energies of micellization/adsorption.     

Solubilization of Phenanthrene and Fluorene in Equimolar Binary Mixtures of Gemini/Conventional Surfactants

abstract This study deals with the enhanced solubilization of polycyclic aromatic hydrocarbons (PAHs) such as phenan-threne (PHE) and fluorene (FLR) in a pure cationic gemini (G6) and three conventiona...     

Synergisms in Binary Mixtures of Anionic and pH‐Insensitive Zwitterionic Surfactants and Their Precipitation Behavior with Calcium Ions

This work aims to investigate synergy in anionic and zwitterionic surfactant mixtures, as they result in better interfacial properties and micellization behavior. Various mixtures of the pH‐insensitive zwitterionic surfactant 3‐(decyldimethylammonio) propanesulfonate (Zwittergent 3–10) and sodium dodecylsulfate (SDS) were prepared in aqueous solution at a range of pH values between 2 and 13. The thermodynamic parameters during mixed surfactant adsorption at the air/water interface are obtained and the results show the mixed surfactant systems having superior properties to the constituent surfactants. Experimentally, the mixed surfactant solutions clearly improve the surface activities by lowering the critical micelle concentration (CMC) and lowering the surface tension at the air/water interface. The synergisms are investigated through the interaction parameters estimated from regular solution theory that is used to quantitatively describe the nonideality of surfactant mixtures. High negative interaction parameters are obtained from these surfactant mixtures. Experimental precipitation phase boundaries of SDS in the presence of CaCl₂ were also investigated in mixtures containing pH‐insensitive zwitterionic surfactant at different pH levels from 2 to 13 and SDS mole fractions of 0.25, 0.50, 0.75, and 1.00. Changes in the precipitation phase boundaries are due to the changes in the speciation or activities of the major components both below and above the CMC. As a result, the precipitation phase boundaries are pH dependent. In addition, mixed micellization and counterion binding to the micelle also change the precipitation phase boundary above the CMC. The activity‐based solubility product of calcium dodecylsulfate is also determined from the precipitation phase boundaries below the CMC. X‐ray diffraction patterns and SEM images confirm that only calcium dodecylsulfate precipitates in the soap scum for all pH and surfactant compositions studied.     

2-丙烯酰胺基辛烷基磺酸钠的合成及其胶束化行为研究

以丙烯腈与1-辛烯为主要原料,合成了表面活性单体2-丙烯酰胺基辛烷基磺酸钠(NaAMC8S)。在n(1-辛烯)∶n(丙烯腈)∶n(发烟硫酸)=1∶6∶1,反应温度25℃,反应时间24h,产品收率(按1-辛烯计)为82.2%。用红外光谱、核磁共振波谱、高分辨质谱和X射线能谱确认了NaAMC8S的化学结构。用电导法与表面张力法测定了NaAMC8S的临界胶束浓度(CMC)。用稳态荧光光谱法测定了CMC和胶束的微极性。结果表明,25℃时,用电导法和表面张力法测得NaAMC8S的CMC分别为44.75mmol/L和51.76mmol/L,对应的表面张力为50.61mN/m;且CMC随温度变化很小。     

Interactions of Glycols with Dodecyl Isothiouronium Cationic Surfactant on the Surface Active Parameters

Surface properties of the dodecyl isothiouronium cationic surfactant in a mixed solvent of water and polyethylene glycol of different molecular weights varied from ethylene glycol to polyethylene glycol-600 were determined using surface tension and conductivity measurements. The results showed an increase in the surface properties including critical micelle concentration, effectiveness and efficiency, compared to the surfactant in pure water as the solvent. The interaction between the cationic surfactant and the glycols was described and the molecular weight of the different glycols was rationalized.     

Interactions of Some Hofmeister Cations with Sodium Dodecyl Sulfate in Aqueous Solution

In this work, we have investigated the influence of some alkali metal ions on the Krafft temperature (T_K) and critical micelle concentration (CMC) of a classical ionic surfactant, sodium dodecyl sulfate (SDS), over a wide range of temperature. The alkali metal cations such as Li⁺, Na⁺, Cs⁺, and K⁺ are found to affect the solubility and hence the T_K of the surfactant. It was observed that kosmotropic Li⁺ lowers the T_K of the surfactant. Due to the common ion effect, the solubility of SDS decreases in the presence of Na⁺, resulting in an increase in the T_K. On the other hand, chaotropic K⁺ and Cs⁺, capable of forming contact ion pairs with the chaotropic dodecyl sulfate ion, lower the solubility and hence elevate the T_K. In terms of decreasing the T_K, the ions follow the trend: Li⁺ > Na⁺ > Cs⁺ > K⁺ except for 0.0025 M CsCl. The added cations screen the charge of the micelle surface and facilitate closer packing of the surfactant with a consequent decrease in the CMC. In terms of the effectiveness in lowering the CMC, the ions follow the order: Cs⁺ > K⁺ > Na⁺ > Li⁺. In the presence of added electrolytes, the γ_CMC values are found to be lower than the corresponding values in pure water. The thermodynamic parameters (Gibbs free energy, enthalpy, and entropy changes) of micellization were calculated to gain insights into the mechanism of the process.     

Interaction of cetyltrimethylammonium bromide with cefixime trihydrate drug at different temperatures and compositions: Effect of different electrolytes

Herein,conductivity measurements have been carried out to explore the interaction between cetyltrimethylammonium bromide(CTAB,a cationic surfactant) and antibiotic drug(cefixime trihydrate(CMT)) in water and also in occurrence of inorganic salts(NaCl,Na_2 SO_4 and Na_3 PO_4) over the temperature range of 303.15-323.15 K with an interval of 5 K.In all cases,two critical micelle concentrations(c~*) were achieved for the CMT-surfactant system.Addition of CMT drug to CTAB solution decreases the values of c~*which indicates the interaction between CMT and CTAB.Both values of c~*for CMT-CTAB mixture in the presence of salts are lower in magnitude compared to the aqueous medium which indicates that micellization of the CMT-CTAB mixed system is favorable in salt solution.The values of △G_m~0 were obtained to be negative indicating the spontaneity of the micellization process and the extent of spontaneity further increases by means of rising temperature.The obtained outcomes from the ΔHm0 and ΔSm0 values disclose that the interactions between CMT and CTAB are mostly electrostatic along with hydrophobic in nature.The thermodynamic parameters of transfer and enthalpy-entropy compensation phenomenon were also determined and discussed in detail.     

Mixed Micellization Behavior of (Chlorpromazine Hydrochloride + Cetyltrimethylammonium Bromide) System in Aqueous Solutions of Glycine

We have examined the mixed micellar behavior of {amphiphilic drug; chlorpromazine hydrochloride (CPZ) + cationic surfactant; cetyltrimethylammonium bromide (CTAB)} at varying mole fractions of CPZ (α_CPZ = 0.2, 0.4, 0.6, and 0.8) in (0.1, 0.3, and 0.5) mol kg⁻¹ glycine_(aq) solutions at 298.15, 308.15, and 318.15 K, by using conductometric, volumetric, isentropic compressibility, UV–visible absorbance, fluorescence, and dynamic light scattering (DLS) techniques. The critical micelle concentration (CMC) values obtained from above measurements have been utilized to calculate the thermodynamic parameters (ΔG^°_m, ΔH^°_m, and ΔS^°_m) and degree of ionization (α) at studied temperatures and concentrations. The partial specific volume (φ_v), partial specific isentropic compression (φ_κ), and isentropic compressibility (κ_s) have been calculated from the experimental density and speed of sound measurements and the results have been used to elucidate different interactions occurring in these systems. These results are further supported by UV–visible absorbance and fluorescence spectroscopic studies. The hydrodynamic diameters (D_h) of the mixed micellar system have been measured from the DLS studies. Thermodynamic and spectroscopic studies depict the dominance of hydrophobic/hydrophilic-hydrophobic interactions between the alkyl (R = C₁₆H₃₃) chain of CTAB or hydrophobic tricyclic scaffolding of CPZ/Br⁻/N⁺-CH₃ group of CTAB or hydrophilic group i.e., tertiary amine portion of CPZ with hydrophobic group of glycine.