Free Energy Of Micellization Research Articles

Synthesis and Biocidal Activity of Some Naphthalene‐Based Cationic Surfactants

In this study, different cationic surfactants were prepared by reacting dodecyl bromide with tertiary amines to produce a series of quaternary ammonium salts that were converted subsequently to stannous and cobalt cationic complexes via complexing them with stannous (II) or cobalt (II) ions. Surface properties such as surface- and interfacial-tension, and the emulsifying power of these surfactants were investigated. The surface parameters including critical micelle concentration, maximum surface excess, minimum surface area, tension lowering efficiency and effectiveness were studied. The free energy of micellization and adsorption were calculated. Antimicrobial activity was determined via the inhibition zone diameter of the prepared compounds, which was measured against six strains of a representative group of microorganisms. The antimicrobial activity of some of the prepared surfactants against sulfate reducing bacteria was determined by the dilution method. FTIR spectra, elemental analysis and a H1 NMR spectrum were examined to confirm compound structure and purity. The results obtained indicate that these compounds have good surface properties and good biocidal effect on broad spectrum of micro organisms.

Effect of chemical structure on the cloud point of some new non-ionic surfactants based on bisphenol in relation to their surface active properties

A series of non-ionic surfactants were prepared from bisphenol derived from acetone (A), acetophenone (AC) and cyclohexanone (CH). The prepared bisphenols were ethoxylated at different degrees of ethylene oxide (27, 35, 43). The ethoxylated bisphenols were non-esterified by fatty acids; decanoic, lauric, myristic, palmitic, stearic, oleic, linoloic and linolinic. Some surface active properties for these surfactants were measured and calculated such as, surface tension [γ], critical micelle concentration [CMC], minimum area per molecule [Amin], surface excess [Cmax], free energy of micellization and adsorption [ΔGmic] and [ΔGads]. At a certain temperature, the cloud point was measured for these surfactants. From the obtained data it was found that; the cloud point is very sensitive to the increase of the alkyl chain length, content of ethylene oxide and degree of unsaturation. The core of bisphenol affected the cloud point sharply and they are ranked regarding bisphenol structure as BA>BCH>BAC. By inspection of the surface active properties of these surfactants, a good relation was obtained with their cloud points. The data were discussed on the light of their chemical structures.

Interactions between Dyes and Cetyl-trimethyl Ammonium Bromide

Abstract Surfactants have been widely used as auxiliaries in many areas of textile finishing. The nature of the interactions between dyes and surfactants is one of the basic piece of information for understanding the process of dyeing and finishing of textile material. The role of attractive interactions between the hydrocarbon tails and repulsive interactions between the surfactant head groups on the micellar association process have been studied. The presented work is oriented on the determination of the critical micelle concentration and molar conductance, in aqueous solution of cationic surfactant cetyltrimethyl ammonium bromide by using the electric conductivity method. From conductivity data parameters for dyes – surfactant interaction such as micellar ionization degree α, counter ion binding and free energy of micellization have been calculated. On the basis of results it is clear that critical micelle concentration depends on the nature of ionic group and concentration of counter ion in solution.

Surface and Biological Activity of Some Prepared Quaternary Ammonium Surfactants

This work investigates the reaction of decyl, dodecyl, and tetradecyl amine with sulphouric acid to produce a quaternary ammonium salt, which consequently converted to copper and cobalt cationic complexes via complexing with copper(II) or cobalt(II) ions. The surface properties studied include critical micelle concentration (CMC), maximum surface excess (Γmax), minimum surface area (Amin), free energies of micellization and adsorption . The interfacial activity (Iactiv.), which is expressed by physicochemical parameter /Amin, was calculated. Antimicrobial activity was determined via the inhibition zone diameter of the prepared compounds, which measured against five strains of group of microorganisms. Antitumor activity for some of these compounds was tested by using Ehrlich Acites Carcinoma (EAC) as a model system of mice cell tumor. Some of these compounds were also tested in vitro on human five monolayer tumor cell lines: MCF7 (breast carcinoma), HEPG2 (liver carcinoma), U251 (brain tumor), HCT116 (colon carcinoma), and H460 (lung carcinoma). Fourier transform infrared spectroscopy (FTIR) spectra, elemental analysis, and nuclear magnetic resonance (1H NMR) spectrum were performed to insure the purity of the prepared compounds.

Thermodynamics of micellization of cationic surfactants based on O-alkyl and O-perfluoro- N, N′-diisopropylisourea: Effect of the counter ion nature

A thermodynamic study on the micellization process of two series of cationic surfactants, viz. the O-dodecyl- N, N′-diisopropylisourea hydrochloride, hydrobromide, and hydroiodide and the O-tridecafluorooctyl- N, N′-diisopropylisourea hydrochloride, and hydrobromide, is reported. In order to explain the effect of the counter ion nature in the micellization process, thermodynamic parameters to include the standard free energy ( Δ G mic ∘ ), enthalpy ( Δ H mic ∘ ), entropy ( Δ S mic ∘ ), and heat capacity ( Δ C p,mic ∘ ) of micellization have been discussed. These parameters are evaluated from the variation of the critical micelle concentration (CMC) with temperature by fitting these values to expressions derived on the basis of a micellization thermodynamic model. The heat capacities of micellization ( Δ C p,mic ∘ ) were determined from the temperature dependence of Δ H mic ∘ . For both surfactant series, the free energy of micellization is weakly temperature dependent and becomes more negative with increasing the size of the counter ion, indicating a more favored micellization. The enthalpy and entropy of micellization decrease strongly with increasing temperature. The heat capacities of micellization ( Δ C p,mic ∘ ) were found to be negative. The enthalpy–entropy compensation phenomenon was observed for all the surfactants studied.

Aggregation of antihistamines in aqueous solution. The effect of electrolyte on the micellar properties of some diphenylmethane derivatives

The effect of sodium chloride on the micellar properties of the antihistamines, dephenhydramine hydrochloride, bromodiphenhydramine hydrochloride, chlorcyclizine hydrochloride and diphenylpyraline hydrochloride in aqueous solution has been investigated by light scattering and viscometric methods. The drugs behaved as typical ionic surfactants showing an increase in aggregation number and decrease in critical micelle concentration as the electrolyte concentration was increased over the range 0.05 to 0.154 mol kg-minus1. A linear relation between log critical micelle concentration and log counterion concentration was established, from which values of the degree of ionization and the free energy of micellization were calculated. The intrinsic viscosity was decreased by the addition of electrolyte and this has been attributed to a decrease in micellar hydration due to a removal of hydrogen-bonded water.

Influence of ionic and nonionic hydrotropes on micellar behavior of a cationic gemini surfactant butanediyl-1,4-bis(dimethylcetylammonium bromide)

Micellization of binary systems of a cationic gemini surfactant butanediyl-1,4-bis(dimethylcetylammonium bromide) (16-4-16) and cationic/nonionic hydrotropes (aniline-hydrochloride, 2-methylanilinehydrochloride, 4-methylanilinehydrochloride, hydroxybenzene, 1,3-benzenediol, benzene-1,2,3-triol) have been studied using a conductometric technique. The critical micelle concentrations (cmc) for different mixing mole fractions at different temperatures have been calculated. To explain and compare the results, theoretical models of Clint, Rubingh and Motomura have been used to obtain the ideal cmc, mixed micelle composition, interaction parameters ( β m ), free energies of micellization, and activity coefficients. The mixtures show nonideal behavior and the interactions between the surfactants and the hydrotropes are synergistic in nature which is confirmed by high negative β m values and low values of the activity coefficients. Thermodynamic parameters were also obtained from the temperature dependence of the cmc values.

Synthesis of Some Novel Sulfonamide Derivatives and Investigating their Biocidal Activity in Cooling Towers

Abstract A novel series of dibenzothiophenedioxide sulphonamide derivatives were synthesized and tested as antimicrobial agents. The chemical structures of the prepared compounds were confirmed by micro elemental analysis, fourier transform infrared (FT-IR) and proton nuclear magnetic resonance spectroscopy (H-NMR). The surface parameters of two of the prepared compounds were determined at 35°C including, surface tension, effectiveness, maximum surface excess and minimum surface area. Also the standard free energy of micellization and adsorption were recorded. The results showed that the prepared sulphonamides have good surface properties and effective antimicrobial activity against thirty three test organisms isolated from cooling towers.

Synthesis and surface properties of semi-fluorinated gemini surfactants with two reactive bromo pendant groups

This paper presents a series of semi-fluorinated gemini surfactants with two bromo pendant groups. It reviews the effect of the number of methylene units in the spacer group between the two hydrophilic quaternary ammonium heads. Critical micelle concentration (cmc) and free energy of micellization ( Δ G M 0 ) of the title surfactants, in aqueous solution, have been investigated as a function of the number n of carbon atoms in the hydrocarbon spacer. We have pointed out a different behaviour as compared to Gemini hydrocarbon homologues. In the present study, when the number of methylene units ( n) in the spacer increases, the cmc first decreases and reaches an optimum for ( n = 6), then it increases linearly from n ⩾ 6. Variations of cmc have been interpreted in terms of conformation changes of the surfactant ion and progressive penetration of the alkyl chain spacer in the micelle hydrophobic core. In this series, the increase of the hydrophobicity seems not to favour the micellisation process as expected, probably impacted by the mutual phobicity of the perfluorinated tails and the hydrocarbon spacer. A minimum is reached for a spacer with six methylene units which seems to be the optimal conformation. The free energy of micellization ( Δ G M 0 ) confirm this tendency.

Micelle formation of nonionic surfactants in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate: Surfactant chain length dependence of the critical micelle concentration

Micellization behavior was investigated for polyoxyethylene-type nonionic surfactants with varying chain length (C n E m ) in a room temperature ionic liquid, 1-butyl-3-methylimidazolium tetrafluoroborate (bmimBF 4). Critical micelle concentration (cmc) was determined from the variation of 1H NMR chemical shift with the surfactant concentration. The logarithmic value of cmc decreased linearly with the number of carbon atoms in the surfactant hydrocarbon chain, similarly to the case observed in aqueous surfactant solutions. However, the slope of the straight line is much smaller in bmimBF 4 than in aqueous solution. Thermodynamic parameters for micelle formation estimated from the temperature dependence of cmc showed that the micellization in bmimBF 4 is an entropy-driven process around room temperature. This behavior is also similar to the case in aqueous solution. However, the magnitude of the entropic contribution to the overall micellization free energy in bmimBF 4 is much smaller compared with that in aqueous solution. These results suggest that the micellization in bmimBF 4 proceeds through a mechanism similar to the hydrophobic interaction in aqueous surfactant solutions, although the solvophobic effect in bmimBF 4 is much weaker than the hydrophobic effect.

Surface Properties and Micellar Molecular Interaction in Binary Systems of a Biosurfactant Sodium Deoxycholate (NaDC) with Conventional Surfactants

AbstractSurface tension for the binary mixtures of a biosurfactant sodium deoxycholate (NaDC) with three different conventional surfactants (p‐(1,1,3,3‐tetramethylbutyl)phenol polyoxyethylene, polyoxethylene‐10‐oleyl ether, and sodium oleate) were measured in buffer solutions at different temperatures. Surface properties were determined as well as the micellar characteristics like composition, micellar molecular interaction parameter (β), activity coefficients (f1, f2), and the free energy of micellization were analyzed using some theoretical models, including Clint, Rubingh, Motomura and Maeda models. The results reveal that all the three investigated systems show non‐ideality in the micelle formation by the deviation in the experimental critical micelle concentration (CMC), f1, f2, and negative β values from the ideal values. The proportion of NaDC in the mixed micelle (X1) calculated by all models increases with increasing the molar fraction of NaDC in solution (αNaDC), but the X1 values are very small even at the high αNaDC. Moreover, by using the Maeda theory, the results suggest the chain‐chain interaction among surfactants does not seem to be strong. It is noted that two break points were observed in the surface tension plots of pure NaOL and NaDC/NaOL mixture solutions. Interestingly, by introducing moderate NaDC or decreasing the temperature, the first break point disappeared for the two systems.

Preparation and Evaluation of Some Surface Active Esters

A series of three homologous pure nonionic surfactants, all mono esters of tri(ethylene glycol), were synthesized. The ester surfactants varied in carbon chine length. The surfactant was characterized by determining surface properties of their solutions, including surface tension, critical micelle concentration, effectiveness (πcmc), efficiency (PC20), maximum surface excess (Γ max ), and minimum surface area (A min ). Standard free energies of micellization and adsorption were calculated. Solubilization behaviors of the synthesized surfactants were measured towards paraffin oil as solubilized material using light transmission technique. Base-catalyzed hydrolysis was investigated by using tensiometry.

Micellization and Interfacial Behaviour of Amitriptyline-Nonionic Surfactant Systems in Aqueous Medium

Abstract By means of surface tension measurement (ring detachment method) mixed micellization and mixed adsorbed film formation were studied between an amphiphilic drug (amitriptyline hydrochloride – AMT) and nonionic surfactants (Tritons and Tweens) at different mole fractions. From the equilibrium surface tension measurements critical micelle concentration (CMC), maximum surface excess (Γmax) and minimum area per surfactant molecule at the air/solution interface (Amin) were obtained. The theories of Rosen, Rubingh and Maeda were applied to analyse the results. Different thermodynamic parameters, viz. free energy of micellization (ΔGo m), standard Gibbs energy of adsorption (ΔGo ads), and minimum energy of surface (Gmin) were evaluated. In the mixed micelles, presence of nonionic surfactants between the head groups of drug molecules decreases the repulsion among head groups. As a result, the CMC and Amin decrease while Γmax increases. Interaction parameters of micelles (βm) and monolayer (βs) indicate that the drug surfactant systems show better interaction at the interface than in micelles.

Novel quaternary ammonium hydroxide cationic surfactants as corrosion inhibitors for carbon steel and as biocides for sulfate reducing bacteria (SRB)

A series of alkyl dimethylisopropylammonium hydroxide cationic surfactants (DEDIAOH, DODIAOH and HEDIAOH) was synthesized and characterized. The surface properties such as the critical micelle concentration (CMC), the effectiveness of surface tension reduction ( Π CMC), surface excess concentration ( Γ max) and surface area per molecule ( A min) have been determined by means of surface tension measurements. The degree of counter ion dissociation ( β) and the free energy of micellization (Δ G mic) were calculated. The corrosion inhibition of the synthesized cationic surfactants on carbon steel surface in 1 M HCl solution was investigated. For this purpose, a series of techniques such as gravimetric measurement, potentiodynamic polarization and scanning electron microscope (SEM) were used. The values of activation energy for carbon steel corrosion and the thermodynamic parameters such as adsorption equilibrium constant ( K ads), free energy of adsorption ( Δ G ads ° ) , adsorption heat ( Δ H ads ° ) and adsorption entropy ( Δ S ads ° ) values were evaluated. Results showed that HEDIAOH had better inhibition effect than DEDIAOH and DODIAOH of the corrosion of carbon steel in 1 M HCl solution and inhibition efficiency is higher than 96% after 24 h at 1 × 10 −2 M concentration of the inhibitor. The inhibition efficiency is discussed in terms of strong adsorption of the inhibitor molecules on the metal surface and formation of a protective film. Scanning electron microscope (SEM) showed a good surface coverage on the metal surface. The Biological activity was examined against sulfate reducing bacteria (SRB) by dilution method.

Mixed micellization of antidepressant drug amitriptyline hydrochloride with cationic surfactants

The surface tension measurements have been carried out on aqueous solutions of antidepressant drug amitriptyline hydrochloride with six cationic surfactants (decyl-, dodecyl-, tetradecyl-, cetyltrimethylammonium bromide, cetylpyridinium bromide and cetylpyridinium chloride) at different mole fractions to study the surface and micellar properties at the interface as well as in the micelles. The properties studied include critical micelle concentration ( cmc), Gibbs surface excess ( Γ max), minimum head group area at the air/water interface ( A min), free energy of micellization ( Δ G m ∘ ), and standard Gibbs energy of adsorption ( Δ G ads ∘ ), while synergistic behavior of drug-surfactant binary mixtures was analysed using Clint's and Rubingh's models. Deviations of cmc from cmc * and X 1 m from X 1 ideal indicate the synergistic behavior (i.e., non-ideal behavior) for the drug-surfactant binary mixtures. The values of interaction parameters β and activity coefficients f 1 and f 2 (for both, in mixed monolayer as well as in mixed micelles) also indicate the synergistic behavior. The excess free energy (Δ G ex) for the drug-surfactant binary mixtures explains stability of mixed micelles in comparison to micelles of pure drug and variation with alkyl chain length of surfactants.

The Preparation and Characterization of Some Novel Quaternary Iminium Salts Based on Schiff-base as a Corrosion Inhibitor

Novel quaternary iminium compounds, namely, N-(4-methoxybenzylidene)-N-benzyldodecyliminium chloride (Ia), N-(4-methoxybenzylidene)-N-benzylhexadecyl iminium chloride (Ib), N-(4-methoxybenzylidene)-N-benzyloctadecyliminium chloride (Ic), and N-benzylidene-N-benzyldodecyliminium chloride, were prepared. The surface properties such as surface and interfacial tension, foaming, and emulsifying power of these surfactants were investigated. The surface parameters including critical micelle concentration (CMC), maximum surface excess (Γmax), minimum surface area (Amin), efficiency (PC20), and effectiveness (πCMC) were calculated. Free energy of micellization (ΔG°mic) and adsorption (ΔG°ads) were calculated.

Counteranion Effect on Micellization of Cationic Gemini Surfactants 14-2-14: Hofmeister and Other Counterions

The effect of counterions was investigated and analyzed to probe the principal ionic effects influencing the micellization behavior of dimeric cationic surfactant ethanediylbis(dimethyltetradecylammonium), referred to as gemini 14-2-14. The 30 counterions were classified to four different families depending on their nature: (1) small and inorganic counterions which are typically taken from the Hofmeister series were studied to focus on the effect of ion type; (2) n-alkyl carboxylate counterions were studied to focus on the effect of the hydrophobicity of counterions; (3) aromatic carboxylate counterions were included to focus on the effect of the position of substitutions; and (4) other counterions were included in order to shed light on other parameters. By investigating the critical micelle concentration (CMC), ionization degree of micelle (alpha), free energy of micellization (DeltaG(M)), and aggregation numbers N of the gemini surfactant with these different types of anions, we demonstrated the effect of different ion properties independently. This approach allowed us to describe the effect of counterions on the micellization behavior of the gemini surfactant in terms of complex interplay between hydrophobicity of anions and other ion properties such as counterion hydration, interfacial packing of ions, and ionic morphology. Indeed, our results clearly demonstrate that a counterion effect on micellization properties cannot be described as a result of one single parameter of ions, as is too often assumed, but rather the balancing effects cooperatively affect the propensity of counterions to form ion pairs with surfactant headgroups and the entropy gain upon micellization. These results provide new insight in understanding the effect of ions on the delicate balance of forces controlling aggregate morphology and solution properties of charged amphiphilic molecules.

Ternary mixtures of alkyltriphenylphosphonium bromides (C12TPB, C14TPB and C16TPB) in aqueous medium: their interfacial, bulk and fluorescence quenching behaviour

The self-aggregation behaviour of ternary mixtures of alkyl (C12-, C14- and C16-) triphenylphosphonium bromides was studied by conductometry and tensiometry. The pure surfactants showed two Critical Micellar Concentrations (CMCs) by conductometry, but their ternary mixtures produce single CMC both by conductometry and tensiometry. The CMC values determined were found to be lower than that obtained from Clint equation suggesting synergistic interaction among the monomers within the micelles. Their bulk properties, like fraction of counterions bound to the micelles and free energy of micellization were evaluated. Interfacial parameters, like surface excess, minimum head group area of monomer and free energy of adsorption were also assessed. Interfacial adsorption was found to be more spontaneous than micellization. The head group area per monomer in ternary systems was larger than pure systems due to stronger electrostatic repulsion among the charged head groups. The values of the packing parameters supported the pure as well as ternary micelles to be spherical. The TPB surfactants efficiently quenched pyrene fluorescence; the performances of the homologues in this respect were assessed.

Effect of spacer length on the micellization and interfacial behavior of mixed alkanediyl-α,ω-bis(dimethylcetylammonium bromide) Gemini homologues

The interfacial and micellization properties of binary and ternary mixtures of Gemini homologues, viz., tetramethylene-1,4-bis(N-hexadecyl-N,N-dimethylammonium bromide), pentamethylene-1,5-bis(N-hexadecyl-N,N-dimethylammonium bromide), and hexamethylene-1,6-bis(N-hexadecyl-N,N-dimethylammonium bromide), with various compositions were investigated at 25 degrees C using conductometric and tensiometric measurements. The micellar and adsorption characteristics like composition, activity coefficients, mutual interaction parameter, minimum area per molecule, free energy of micellization and adsorption have been evaluated and compared. The ideality/nonideality of the mixed micelles were tested in light of Clint, Rubingh, and Rubingh-Holland approaches. The mixed systems were found to undergo synergistic interaction, more so in mixed monolayer than in mixed micelle formation, and the micellar and interfacial properties were found to depend on the selection of surfactant pairing.

PHYSICAL CHEMICAL STUDIES OF THE SURFACTANT DILAURYLDIMETHYLAMMONIUM BROMIDE (DLDMAB): AGGREGATION AND CATALYTIC PROPERTIES

The micellization of dilauryldimethylammonium bromide (DLDMAB) in water was studied by using surface tension measurements. The critical micellar concentration (CMC) was determined at 25°C, 32°C and 40°C and thermodynamic parameters such as the free energy of micellization (∆G°mic), enthalpy (∆H°mic), and entropy (∆S°mic) of micellization were measured. The CMC at 25°C was 4.93 x 10-5 M and the corresponding values of the thermodynamic parameters were: ∆G°mic = -5.87 kcal/mol; ∆H°mic = -1.12 kcal/mol and ∆S°mic = +16.00 e.u. Micelles of the surfactant DLDMAB act as catalysts for the alkaline hydrolysis of p-nitrophenyl diphenyl phosphate (NPDPP) with a maximum catalytic factor of approximately 120 compared to 80 for CTAB. Typical activation parameters measured for 1.00 x 10-3 M surfactant and 0.005 M NaOH were: Ea = 9.7 kcal/mo/; ∆H°≠ = 9.1 kcal/mol; ∆G°≠ = 19.6 kcal/mol and ∆S°≠ = -33.9 e.u. The kinetic results were also analyzed in terms of the pseudo-phase ion-exchange models (PPIE) and showed that the model is applicable to describe the experimental results.