Energy Of Micellization Research Articles

Behavior of hexadecyltrimethylammonium bromide and Triton X-100 mixture in the bulk phase of aqueous solution in the presence of methanol and propanol

Measurements of density, dynamic viscosity and specific conductivity of the aqueous solutions of p-(1,1,3,3-tetramethylbutyl)phenoxypoly(ethylene glycol) (Triton X-100 or TX-100) and hexadecyltrimethylammonium bromide (CTAB) with methanol or propanol were made. The surfactant mixture concentration ranged from 1×10−6 to 3×10−2M and the mole fraction of alcohol changed from 0 to 1. From the obtained results the critical aggregation concentration (CAC) of alcohol and the critical micelle concentration (CMC) of surfactant mixture were determined. It proved that the short-chain alcohols considerably affect the CMC of surfactants, but surfactants only slightly affect the CAC of alcohols. Moreover, surfactants form micelles only in the range of alcohol concentration below its CAC. Methanol can be treated only as a cosolvent while propanol depending on its concentration range acts as both a cosurfactant and cosolvent. The apparent and partial molar volumes of alcohol, water and surfactant mixture were determined from the commonly known equations. It appeared that these volumes can be also predicted on the basis of the bond lengths and angles between atoms in the molecules as well as the average distance between molecules by approximating the volume of certain functional groups by cages. The composition of mixed TX-100+CTAB micelles was determined from the Rosen's theory of regular solutions. The standard Gibbs free energy of micellization and aggregation was also evaluated. The specific conductivity changes for the studied solutions with methanol or propanol were compared.

The effect of salts on micellization in C12mimBr/Triton X-100 aqueous mixtures and on the surface properties of the solutions

Herein, we report our studies on the mixed aqueous solutions of 1-dodecyl-3-methylimidazolium bromide (C12mimBr) and Triton X-100 in the presence of sodium bromide and sodium chloride by surface tension and conductivity measurement methods. The critical micelle concentration and several other parameters such as maximum surface excess, minimum area per molecule and surface pressure at the CMC were calculated from the data of surface tension investigation. The critical micelle concentration values decreased with the increase of salt concentration. Rubingh’s theory was applied to calculate the mole fraction (X 1) of C12mimBr in the mixed systems. The results showed that X 1 increased most significantly with the concentration of the salt in the presence of NaBr. The values of standard Gibbs energies of micellization and interfacial adsorption have also been calculated; both were found to be negative for all systems, indicating the spontaneity of micellization and adsorption of the surfactants.

Mixed Micellization and Interfacial Properties of Ionic Liquid‐Type Imidazolium Gemini Surfactant with Amphiphilic Drug Amitriptyline Hydrochloride and its Thermodynamics

AbstractThe thermodynamics of mixed micellization of amitriptyline hydrochloride (AMT) with ionic liquid‐type imidazolium gemini surfactant ([C10‐4‐C10im] Br2), was investigated at different mole fractions and temperatures by surface tension measurements. The deviation of the critical micelle concentration (CMC) from the ideal critical micelle concentration (CMC*), micellar mole fraction () from ideal micellar mole fraction (), the values of interaction parameter () and activity coefficients () (for both mixed micelles and mixed monolayer) explained the non‐ideal behavior (i.e., synergistic behavior) of binary mixtures. The excess free energy (∆Gex) for the AMT‐[C10‐4‐C10im] Br2 binary mixtures explained the mixed micelles stability in comparison to micelles of [C10‐4‐C10im] Br2 and pure AMT. Interfacial parameters, i.e., Gibbs surface excess (), minimum head group area at air/water interface (), free energy of micellization (), and standard Gibbs energy of adsorption (∆Gadso) were also evaluated for the systems. The standard entropy of adsorption (∆Sadso) was found higher than the standard entropy of micellization (∆Smo) at all mole fractions of AMT (α1).

Interactions between cationic surfactants and 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin tetrasodium salt as seen by electric conductometry and spectroscopic techniques

Abstract The interaction between the anionic porphyrin 5,10,15,20-tetrakis(4-sulfonatophenyl)porphyrin tetrasodium salt (Na4H2TPPS4) and alkyltrimethylammonium bromides (CnTAB), with different alkyl chain lengths (n = 12 and 16), in aqueous solutions have been studied by using electrical conductivity, potentiometry and spectroscopic (UV–vis and fluorescence) techniques. The effect of surfactant concentration in a concentration range involving the pre- and post-micelle region and temperature was evaluated. Interactions between surfactant and porphyrin lead to a three well-defined regions. At the lowest molar ratios, r = [CnTAB]/[Na4H2TPPS4] occur the disaggregation and deprotonation of porphyrins concomitantly with the formation of surfactant–porphyrin aggregates. These aggregates have a stoichiometry lower than the simple charge neutralization as due to the occurrence of multiple equilibria involving porphyrins. This also suggests that although electrostatic interactions are important, they are not the only driven-force for interaction. When surfactant is in excess (porphyrin saturation concentration The effect of porphyrin concentration and temperature on the micellization properties of surfactants was also analyzed, showing that temperature has no significant effect on the cmc of C16TAB. However, looking to the free energy of micellization the effect of temperature favours the micellization process, being such effect more pronounced for the most hydrophobic surfactant. This suggests that the degree of dissociation of counter ions in the micelle plays an important role on the micellization process in the presence of porphyrins.

Effect of tartarate and citrate based food additives on the micellar properties of sodium dodecylsulfate for prospective use as food emulsifier

Citrate and tartarate based food preservatives can be used to enhance the emulsifying properties of sodium dodecylsulfate (SDS) based micellar system and thus making it appropriate for food applications. Exploration of interactions between the two species is the key constraint for execution of such ideas. In this work various micellar and thermodynamic parameters of SDS like critical micellar concentration (CMC), standard Gibbs free energy of micellization (ΔG0mic.) etc. have been calculated in different concentrations of disodium tartarate (DST) and trisodium citrate (TSC) in the temperature range (288.15–318.15)K from the conductivity and surface tension measurements. The parameters obtained from these studies reveal the competitive nature of both the additives with SDS for available positions at the air/water interface. TSC is found to be more effective additive in order to make SDS micellar system better for its potential applications as food emulsifier.

Synthesis and Surface Properties of a Novel Sodium 3‐(3‐Alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate at the Air–Water Interface

AbstractThe present paper describes the synthesis and evaluation of surface properties of a novel series of anionic surfactant, namely sodium 3‐(3‐alkyloxy‐3‐oxopropoxy)‐3‐oxopropane‐1‐sulfonate with varying alkyl chain length (C8–C16). Synthesis involves initial formation of the 3‐alkyloxy‐3‐oxopropyl acrylate along with fatty acrylate during the direct esterification of fatty alcohol with acrylic acid in the presence of 0.5 % NaHSO4 at 110 °C followed by sulfonation of the terminal double bond of the 3‐alkyloxy‐3‐oxopropyl acrylate. Synthesized compounds were evaluated for surface and thermodynamic properties such as critical micelle concentration (CMC), surface tension at CMC (γcmc), efficiency of surface adsorption (pC20), surface excess (Γmax), minimum area per molecule at the air–water interface (Amin), free energy of adsorption (∆G°ads), free energy of micellization (∆G°mic), wetting time, emulsifying properties, foaming power and calcium tolerance. Effect of chain length on CMC follows the classic trend, i.e. decrease in CMC with the increase in alkyl chain length. High pC20 (>3) value indicates higher hydrophobic character of the surfactant. These surfactants showed very poor wetting time and calcium tolerance, but exhibited good emulsion stability and excellent foamability. Foaming power and foam stability of C14‐sulfonate were found to be the best among the studied compounds. Foam stability of C14‐sulfonate was also studied at different concentrations over time and excellent foam stability was obtained at a concentration of 0.075 %. Thus this novel class of surfactant may find applications as foam boosters in combination with other suitable surfactants.

Effect of Polar Organic Solvents on Self‐Aggregation of Some Cationic Monomeric and Dimeric Surfactants

AbstractSurface and micellization behavior of some cationic monomeric surfactants, viz., cetyldiethylethanolammonium bromide (CDEEAB), cetyldimethylethanolammonium bromide (CDMEAB), tetradecyldiethylethanolammonium bromide (TDEEAB) and dimeric surfactants, i.e., alkanediyl‐α, ω‐bis(dimethylhexadecylammonium bromide) (C16‐s‐C16, 2Br− where s = 4, 12), butanediyl‐1,4‐bis(dimethyldodecylammonium bromide (C12‐4‐C12, 2Br−) and 2‐butanol‐1,4‐bis(dimethyldodecylammonium bromide) (C12‐4(OH)‐C12, 2Br−), was studied in water‐organic solvents [10 and 20 % v/v ethylene glycol (EG) and diethylene glycol (DEG)] by conductivity, surface tension and steady‐state fluorescence methods at 300 K. The main focus of the present work is on the study of the effect of organic solvents on the critical micelle concentration (CMC), Gibbs free energy of micellization (ΔG°m), Gibbs free energy of transfer (ΔG°trans), Gibbs adsorption energy (ΔG°ads) and some interfacial parameters such as the surface excess concentration (Γmax), minimum area per surfactant molecule (Amin) and surface pressure (πCMC). The aggregation number (Nagg) and Stern‐Volmer quenching constant (KSV) were also determined by the steady‐state fluorescence method. It was observed that Nagg decreased with increasing volume percent of organic solvent. The results exhibited an increase in CMC in water‐organic solvents as compared to the respective surfactants in pure water. The negative values of ΔG°m and ΔG°ads indicate a spontaneous micellization process. The thermodynamics of micellization revealed that the micellization‐reducing efficiency of glycols increases with the concentration and the number of ethereal oxygens in the glycol.

Synthesis, characterization, and in vitro antifungal activity of anionic and nonionic surfactants against crop pathogenic fungi

Fungi have long been identified as causal agents of plant diseases. The development of plant antifungal activity was attempted by synthesis of a new type of anionic and nonionic surfactant. The surface properties were studied, including critical micelle concentration (CMC), effectiveness (πcmc), maximum surface excess (Γmax), and minimum surface area (Amin). Free energy of micellization and adsorption was calculated (ΔG°mic and ΔG°ads). The antifungal activity of the prepared surfactants was verified in vitro by the poisoned food technique against eight phytopathogenic fungi: Colletotrichum dematium, Drechslera hawaiiensis, Fusarium oxysporum, Fusarium solani, Humicola fuscoatra, Pestalotia laurocerasi, Phoma spp., and Phytophthra. The results reported that the percentage inhibition of mycelial growth increases with increasing concentrations of the surfactant for all fungal species used. These results indicated that the surfactant inhibited the mycelial growth of all fungal species in a dose-dependent manner. Blend surfactants have a potential antifungal effect for the control of some phytopathogenic fungi.

Effect of surfactant structure on the mixed micelle formation of cationic gemini–zwitterionic phospholipid systems

The micellization behavior of mixed zwitterionic/cationic solutions, that is, of zwitterionic phospholipid, 1, 2-dioctanoyl-sn-glycero-3-[phospho-L-serine] (sodium salt) (PL) and cationic gemini surfactants, alkanediyl-α,ω-bis(dimethylalkylammonium bromide (alkyl: 14 or 16 and alkane: butane, pentane or hexane) (m-s-m), have been studied by surface tension measurements. Various physicochemical properties, viz., critical micelle concentration (cmc), surface excess concentration (Γmax), minimum area per molecule (Amin), interaction parameters (βm, βσ), and thermodynamic parameters such as standard Gibbs energy of micellization (ΔGmic°), standard Gibbs energy of adsorption (ΔGads°), and excess free energy of mixing (ΔGexm,ΔGex°), have been evaluated. The obtained results indicate that the mole fraction of PL in the mixed micelles, calculated on the basis of Rubingh's model, is different from stoichiometric mole fraction of PL (α1). The negative values of ΔGmic° and ΔGads° show that the micelle formation and adsorption of surfactants at the air/solution interface is energetically favorable with the magnitude of ΔGads° greater than that of ΔGmic°. The negative values of ΔGexm and ΔGexσ indicate better stability of the mixed systems. The insights presented herein on the gemini-phospholipid mixed micelle properties may find use towards their applications in the relevant areas of solubilization/drug delivery/etc.

Analysis of the Interactions of Polyvinylpyrrolidone with Conventional Anionic and Dimeric Anionic Surfactant

Classical physical method has been applied in the present study of interaction between water soluble polymer with anionic dimeric and conventional anionic surfactants. Micellization activity of carboxylate-based anionic dimeric (CAD) as well as sodium dodecyl sulfate (SDS) surfactants in the presence of nonionic polymer, that is, polyvinylpyrrolidone (PVP), has been studied through conductometric and surface tensiometric measurements. From these methods the critical aggregation concentrations (CACs), critical micelle concentrations (CMCs), and the effective degree of counterion binding (β) were determined. For the evaluation of behavior of CAD toward the PVP various thermodynamic properties viz. standard Gibbs energy of micellization, standard enthalpy, and entropy of micellization of CAD/PVP mixed system have also been estimated and discussed. The results exhibit that anionic dimeric surfactant interacts strongly with PVP as compared to conventional surfactant.

Surface tension and UV–visible investigations of aggregation and adsorption behavior of NaC and NaDC in water–amino acid mixtures

Aqueous micellar solutions of bile salts, sodium cholate (NaC) (1–30mmolkg−1) and sodium deoxycholate (NaDC) (1–17mmolkg−1) in the absence and presence of amino acids viz. glycine, leucine, methionine, and histidine (0.1molkg−1) have been examined by surface tension and UV–visible measurements at different temperatures (293.15–318.15K). From the surface tension study, critical micelle concentration (CMC) values of bile salts have been calculated and reviewed in terms of effect of amino acids on the hydrophobic character of bile salt–amino acid complex. Further, the adsorption behavior of NaC and NaDC in aqueous solution of amino acids has been analyzed with the help of interfacial parameters like maximum surface excess concentration (Γmax), minimum area per surfactant molecule (Amin), surface pressure at CMC (ΠCMC), efficiency in reducing surface tension (pC20), and adsorption at the air/water interface relation to micellization (CMC/C20). The thermodynamic parameters, standard free energy of micellization (ΔGm°), standard Gibb’s free energy of adsorption (ΔGad°), and standard free energy of transfer (ΔGtr°) have also been calculated. UV–visible studies, by using pyrene as a probe, have also been carried out in order to substantiate the CMC values derived from surface tension studies.

Influence of Sodium Salts on the Micellization and Interfacial Behavior of Cationic Surfactant Dodecyltrimethylammonium Bromide in Aqueous Solution

Micellar and surface properties of aqueous dodecyltrimethylammonium bromide (DTAB) solutions have been studied in the absence and presence of several sodium salts including NaCl, NaH2PO4, Na2HPO4, Na2CO3, Na2SO4, Na3PO4, and Na3Cit. The values of critical micelle concentration (cmc), degree of anionic binding (β), surface tension at the cmc (γcmc), adsorption efficiency (pC20), effectiveness of surface tension reduction (Πcmc), maximum surface excess concentration (Γmax), minimum surface area per molecule (Amin) at interface of air–liquid, standard Gibbs free energy of micellization (ΔmicG°), and adsorption at air/water interfaces (ΔGad°) were evaluated from the conductivity and surface tension measurements at 298.15 K. The results show that all salts effectively reduce the cmc values of the cationic surfactant DTAB. The ability of the anions to promote the micellization of DTAB decreases in the order of Cit3– > PO43– > SO42– > CO32– > HPO42– > Cl– > H2PO4–. The effect of anions of the added salts on the ...

Self-aggregation of surfactant ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride: tensiometric, microscopic, and spectroscopic studies.

We have investigated the effect of salt additives (NaCl, Na₂SO₄, Na₃PO₄, NaTos, and NaAn) on the aggregation behavior of a cleavable biodegradable ester-bonded dicationic gemini surfactant, ethane-1,2-diyl bis(N,N-dimethyl-N-hexadecylammoniumacetoxy) dichloride (16-E2-16). A multitechnique approach employing tensiometry, fluorescence, proton magnetic resonance (¹H NMR), transmission electron microscopy (TEM), absorption spectrophotometry (UV), and Fourier transform infrared spectroscopy (FTIR) was utilized to probe physicochemical fluctuations. Appreciable changes were observed in various physicochemical parameters, viz., critical micelle concentration (CMC), surface excess concentration (Γ(max)), minimum area per headgroup (A(min)), free energy of micellization (ΔG(mic)°), free energy of adsorption (ΔG(ads)°), and aggregation number (N(agg)). Counter ions were found to affect through electrostatic and hydrophobic influence obeying the overall trend as NaAn > NaTos > Na₃PO₄ > Na₂SO₄ > NaCl. ¹H NMR, TEM, UV, and FTIR results reveal microstructure evolution and phase transitions. These results thus provide deeper insights in understanding of self-aggregation and microstructure evolution of biocompatible (green) aqueous systems of the gemini surfactant and their implications in the biomedical and pharmaceutical world, which could be helpful to improve their bioavailability and other biochemical aspects like drug delivery and gene transfection.

Micellization Behaviour of m-E2-m Biodegradable Gemini Surfactants in Presence of Sodium Alkanoates (Sodium Propionate, Sodium Hexanoate, Sodium Decanoate)

Abstract The present study involves the micellization of novel biodegradable gemini surfactants (1,2-diyl-bis(N,N-dimethyl-N-alkyl-ammoniumacetoxy) dichlorides, m-E2-m; m = 12,14,16 is the number of carbon atoms in the tail and E2 represents the diester-group-containing spacer) in presence of sodium alkanoates (sodium propionate, sodium hexanoate, sodium decanoate). The techniques of tensiometry and spectrofluorimetry were utilized to probe the changes in various physicochemical parameters, viz. critical micellar concentration (CMC), surface excess concentration (Γmax), minimum area per head group (Amin), Gibbs free energy of micellization (ΔG° mic), Gibbs free energy of adsorption (ΔG° ads), aggregation number (Nagg) and local polarity index (I1/I3). Results depict that the alkanoates are effective in bringing significant changes in the physicochemical parameters of the m-E2-m geminis; the order being followed is NaDec > NaHx > NaPr. Both hydrophobic and electrostatic factors were found to be contributive. This study can be helpful to understand tuning and evolution of biodegradable microstructures in amphiphilic salt environments, which may have implications in biomedical research (gene transfection and drug delivery).

Effect of adsorption site potential on adsorption of sodium dodecylbenzenesulfonate in highly humic volcanic ash soil

Sodium dodecylbenzenesulfonate (DBS) is a very useful and widely used anionic surfactant. This surfactant sometimes creates environmental problems when it is released into the water environment. However, the factors influencing the adsorption of DBS in soil have not been studied well. In this study, the influence of the potential at the adsorption site on the adsorption of DBS in a soil was first elucidated using a theoretical adsorption equation. The soil was a highly humic soil with a negative charge. The amount of DBS adsorbed was measured with a batch method for different electrolyte concentrations of sodium chloride (NaCl) at pH 4.5 and 6.5. The adsorption site potential of the soil was obtained with the modified Langmuir adsorption equation. The adsorption of DBS decreased as the electrolyte concentration decreased and as the pH increased because the repulsive electric potential between DBS and the soil increased. These results were confirmed by the obtained adsorption site potential and the measured electrophoretic mobility. The difference between the adsorption of DBS with a linear and with a branched carbon chain was also detected, and this difference was related to the free energy of micellization. Because DBS adsorption is strongly affected by electrolyte concentration and pH, these two factors must be carefully considered to predict the fate of DBS in soil and water environments.

Modulation of Micellization Behavior of Cetyltrimethylammonium Bromide (CTAB) by Organic Anions in Low Concentration Regime

Micellization of the cationic surfactant cetyltrimethylammonium bromide (CTAB) in dilute aqueous solutions of sodium butyrate (Na-Bu), sodium benzoate (Na-Ben) and sodium salicylate (Na-Sal) at different concentrations, viz. 0.005, 0.01, and 0.05 mol·L−1, has been investigated. Conductivity, steady-state fluorescence, dynamic light scattering (DLS), atomic force microscopy (AFM), and 1H NMR techniques shed light on different aspects of micellization. Various micellization parameters such as critical micelle concentration (cmc), degree of ionization of micelle (α), and standard Gibbs energy of micellization ( $$ \Delta G_{\text{m}}^{\text{o}} $$ ) have been obtained from conductivity measurements. Steady-state fluorescence has provided useful information about the cmc, polarity of cybotactic region and aggregation number of micelles of CTAB using pyrene as fluorescent probe in various aqueous salt solutions. The data have been analyzed in terms of hydrophobicity/hydrophilicity and polarizability of the anions of the added electrolytes. The content and nature of organic anions governs the shape and size of the micelles as revealed by DLS and AFM measurements. In the dilute concentration regime of added electrolytes, contrary to most of the reported studies pertaining to very high concentration of added electrolyte, no worm like micelles forming a gel like structure have been observed. 1H NMR experiments provided information about the sites of interaction of anions of added electrolytes with the surfactant head group.

Synthesis and evaluation of some derivatives of polysiloxanes

Silicone surfactants have been widely used in our daily life and many industrial fields on the basis of their unusual properties. Only in the past decades has the use of silicone as a hydrophobic building block for the preparation of surfactants become common. The recent trend to combine silicone, polyoxyalkylene and carbohydrate moieties in the same molecule has resulted in a plethora of new compounds with new properties.In this article, we report the preparation of a series of “glycopolysiloxanes” surfactants with different molecular weights. They were structurally characterized by IR, 1H NMR and MS.Specifically, the critical micelle concentration (cmc), effectiveness of surface tension reduction (πcmc), maximum surface excess (Γmax), minimum surface area (Amin) and standard free energies of micellization (ΔG°mic) and adsorption (ΔG°ads) have been determined from aqueous surface tension measurements using Du-Nouy Tensiometer (KRUSS K6 type 4851) with a platinum ring. All the surfactants have good surface properties and have low cmc.The bacteriostatic power of these polymers was tested and compared under the same conditions in aqueous solution against common strains of Gram positive bacteria and strains of Gram negative bacteria.

Thermodynamics of Micelle Formation of Gemini Surfactants Hexylene-1,6-bis(dimethyloctylammonium bromide) and Dodecylene-1,12-bis(dimethyloctylammonium bromide) by Electric Conductance Mesurements

The subject of this study concerns the aggregation process of cationic gemini surfactants with formulas 8–6–8 and 8–12–8. Conductivity measurements carried out within the temperature range of (288.15–323.15) K made it possible to determine the values of critical micelle concentration and dissociation degree of micelles for the system investigated within this temperature range. Using various models, the basic thermodynamic functions (enthalpy, entropy, and free Gibbs energy of micellization) were determined. The data obtained allowed us to assess their usability and the effect of temperature on the micellization process. It has been shown that an increase in temperature causes a linear decrease in the values of ΔHmic and ΔSmic, which results from the increase in the repellent interaction force between ammonium groups and increase in the disorder of water structure influencing the hydrophobic effect. Slight changes in the free enthalpy indicate the occurrence of enthalpy–entropy compensation. It has been sh...

Comparative Investigations on Mixing Behaviors of Cationic Gemini Surfactant with Surface Active Ionic Liquid in Water and in Ethylammonium Nitrate

The properties of mixed surfactants of 1-tetradecyl-3-methylimidazolium bromide (C14mimBr) and the gemini surfactant N,N′-bis(dimethyldodecyl)-1,2-ethanediammonium dibromide (12-2-12) in water and in ethylammonium nitrate (EAN) were studied by surface tensiometry. The critical micelle concentration (cmc) values of the mixed surfactants were determined and found to be much larger in EAN than in water. The nonideal mixing behaviors were observed at the air/solvent interface and in the mixed micelle both in water and in EAN. The surface pressure at the cmc (πcmc), the maximum surface excess (Γmax), the minimum surface area per molecule (Amin), the standard Gibbs free energies of micellization (ΔGm0) and adsorption (ΔGads0), and the excess Gibbs free energy of mixed micelles (ΔGE) were determined. It was found that physicochemical properties of C14mimBr/12-2-12 mixed systems in water and in EAN were significantly different, which was discussed in terms of different properties of the solvents.

Characteristics of mixed systems of phenol red and cetylpyridinium chloride

Dye–surfactant systems known to exhibit two critical micelle concentrations (cmcs) are not many and the behavior of such systems in the mixed form has not been fully explored and reported. Phenol red (PR) and cetylpyridinium chloride (CPC) form one such dye–surfactant pair and its mixtures are studied here in the entire composition range using surface tension, conductance and UV–Visible spectroscopy methods. In this mixed system, mixed micelles are formed with one cmc in the region of 0<αCPC<0.5, while mixed micelles as well as micelles of the surfactant alone are formed with two cmcs if 0.5≤αCPC<1 (αCPC is the mole ratio of CPC to PR in solution). The mixture shows strong synergism in cmc with high negative value for interaction parameter. The bathochromic shift of the 432nm band indicated hydrogen bonding between PR− species in the region of αCPC<0.4 and this hydrogen bonding weakened more in the presence of CPC due to ion pair formation than in the presence of a non-ionic surfactant TX-100. The relative amount of CPC in the mixture and the nature of the surfactant are found to influence the maximum wavelength of the PR2− band also. The excess standard free energy of micellization has a linear correlation with the interaction parameter. Surface excess values of the individual components of the mixed system were evaluated. The compositions of the mixed micelle and the adsorbed layer reveal that some CP+ monomers also aggregate/adsorb along with the CP+–PR− ion pairs.