Mixed micellar properties of cationic trimeric-type quaternary ammonium salts and anionic sodium n-octyl sulfate surfactants

The properties of quaternary ammonium salt-type cationic trimeric surfactants (m-2-m-2-m, m represents the carbon atom number in alkyl chain lengths of 8, 10, and 12) and oppositely charged anionic monomeric surfactant, sodium n-octyl sulfate (SOS), were characterized by employing several techniques such as static surface tension, fluorescence spectroscopy, and dynamic light-scattering measurements. The critical micelle concentrations (cmc) of m-2-m-2-m were much lower than those of the corresponding dimeric and monomeric surfactants, and decreased with increasing chain length. The addition of SOS to m-2-m-2-m solutions resulted in a further decrease of the cmc. The mixed surfactants showed higher efficiencies in lowering the surface tension than the individual surfactants. The fluorescence measurements suggested the formation of mixed micelles with a hydrophobic environment in the solutions even at lower concentrations. The dynamic light-scattering study indicated the presence of two different kinds of aggregates with different hydrodynamic diameters. The larger one was attributed to the mixed micelle of m-2-m-2-m and SOS. These results indicated a decline of the electrostatic repulsion between cationic head groups through the incorporation of anionic surfactant into the mixed surfactants.     

Zwitterionic heterogemini surfactants containing ammonium and carboxylate headgroups. 1. Adsorption and micellization

Zwitterionic heterogemini surfactants with two hydrocarbon chains and two different hydrophilic groups, N,N-dimethyl-N-[2-(N'-alkyl-N'-beta-carboxypropanoylamino)ethyl]-1-alkylammonium bromides (2C(n)AmCa, where n represents the hydrocarbon chain lengths of 8, 10, 12, and 14), were synthesized by N,N-dimethylethylenediamine with alkyl bromide, followed by reaction with succinic anhydride. One of the hydrophilic groups is a carboxylate anion, and the other is an ammonium cation. Their physicochemical properties were characterized by measuring equilibrium and dynamic surface tension, fluorescence intensity of pyrene, and light-scattering intensity. A relationship between a logarithm of critical micelle concentration (cmc) and hydrocarbon chain length showed a linear decrease upon increasing chain length and then a departure from linearity at n = 14. This is due to the existence of premicellar aggregations at concentrations below the cmc for n = 14. The surface tension of 2C(n)AmCa reached 27-30 mN m(-1) at each cmc, indicating efficiencies typical of hydrocarbon chain surfactants. The adsorbing rate at the air/water interface became slow with an increase of the chain length. From the fluorescence intensity ratios of 373 and 384 nm using pyrene as a probe, for n = 8, 10, and 14, the pyrene was solubilized in surfactant micelles at around the cmc, whereas for n = 12 the pyrene was solubilized from a concentration of 10-fold the cmc. The scattering intensities by dynamic light scattering also increased from around these concentrations for each chain length, showing the formation of aggregates in solution.     

Synthesis and surface properties of anionic gemini surfactants with amide groups

Novel anionic gemini surfactants, 1,2-bis(N-beta-carboxypropanoyl-N-alkylamino)ethane (2CnenAm; n is hydrocarbon chain length of 6, 8, 10, 12, or 14), with two hydrocarbon chains, two carboxylate groups, and two amide groups, were synthesized by three-step reactions. Their solution properties were characterized by equilibrium and dynamic surface tension, steady-state fluorescence spectroscopy of pyrene, and dynamic light-scattering techniques. The surface tension measurements of 2CnenAm give low critical micelle concentrations (cmc), great efficiency in lowering the surface tension, and strong adsorption at air/water interface. Gemini surfactants behave normally with the logarithm of cmc decrease linearly with the chain length. In addition, adsorption and micellization behavior of 2CnenAm was estimated by parameter of pC20, cmc/C20, and standard free energy (DeltaG(0)mic and DeltaG(0)ads); they are significantly influenced by hydrocarbon chain length, and the adsorption is promoted more than the micellization as chain length becomes longer. The results of dynamic light-scattering and fluorescence quenching indicate that small micelles of 2CnenAm are observed at the concentrations above the cmc, and further large particles are also seen. Further, from the dynamic surface tension measurements, it is found that the shorter hydrocarbon chain length of 2CnenAm, the faster the rate of decrease of surface tension.     

Adsorption and aggregation properties of heterogemini surfactants containing a quaternary ammonium salt and a sugar moiety

A novel heterogemini surfactant comprising two hydrocarbon chains and two different hydrophilic groups such as a quaternary ammonium cation and gluconamide nonion N,N-dimethyl-N-[2-(N'-alkyl-N'-gluconamide)ethyl]-1-alkylammonium bromides (2CnAmGlu, where n represents hydrocarbon chain lengths of 8, 10, 12, and 14) was synthesized by reacting N,N-dimethylethylenediamine with alkyl bromide, followed by a reaction with 1,5-D(+)-gluconolactone. The adsorption properties of 2CnAmGlu were characterized by surface tension measurements made using the Wilhelmy plate method, and their aggregation properties were investigated by dynamic light scattering and cryogenic transmission electron microscopy techniques. The relationship between the hydrocarbon chain length and the logarithm of the critical micelle concentration (cmc) for 2CnAmGlu exhibited a linear decrease when the chain length was increased up to 12 and then a departure from linearity at n=14. The surface tension reached 24-26 mN m-1 at each cmc, indicating high efficiency in lowering the surface tension of water. Furthermore, it was found that the structure of the aggregate formed for 2CnAmGlu in solution was influenced by the hydrocarbon chain length; that is, for n=10 and 12, micelles with a hydrodynamic radius of 2-5 nm were formed, whereas vesicles were also observed for n=14.     

光敏季铵盐Gemini表面活性剂a4-6-m在气/液界面的吸附

合成了3种不对称结构的季铵盐Gemini表面活性剂a4-6-m, 分子的一根疏水链是偶氮苯为端基的4个亚甲基链, 另一根是不同长度的脂肪链(m=12, 14, 16). 研究结果表明, 反式偶氮苯封端的a4-6-m在气/液界面上以直立方式排列, 偶氮苯端基间的π-π相互作用导致吸附分子较为紧密地排列, 但吸附层外表面含有偶氮苯成分使临界胶束浓度(cmc)时的表面张力(γcmc)较大. 紫外光激发使反式结构偶氮苯变为顺式结构, 这些极性较强的顺式偶氮苯夹杂在直立的烷烃链间, 增强的偶极-偶极相互作用促进了分子紧密排列, 使分子占据面积(Amin)略微减小. 增长脂肪链长度有助于降低临界胶团浓度和C20(使水的表面张力降低20 mN·m-1时所需的表面活性剂浓度), 但对γcmc影响不大.     

Supra-long chain surfactants with double or triple quaternary ammonium headgroups

Novel supra-long chain surfactants with double or triple quaternary ammonium salts (C(n)-2Am, C(n)-3Am, in which n represents a hydrocarbon chain length of 18, 20, and 22) were synthesized, and electrical conductivity and surface tension were used to characterize their properties depending on both the hydrocarbon chain length and number of hydrophilic groups. The Krafft temperatures decreased remarkably with an increase in the quaternary ammonium headgroups, resulting in a high solubility in water. The critical micelle concentration (cmc) increased with an increase in the number of quaternary ammonium moieties in the hydrophilic group, and the difference in the cmc was smaller for C(n)-2Am and C(n)-3Am than for C(n)-2Am and C(n)-Am of alkyltrimethylammonium bromide. The surface tension at the cmc was approximately 45 and 48 mN m(-1) for C(n)-2Am and C(n)-3Am with n=18-22, respectively. This indicated that the supra-long chain surfactants could not efficiently adsorb at the air/water interface and orient by themselves, as is known for conventional surfactants.     

Adsorption and micellization behavior of novel gluconamide-type gemini surfactants

The adsorption and micellization behavior of novel sugar-based gemini surfactants (N,N(')-dialkyl-N,N(')-digluconamide ethylenediamine, Glu(n)-2-Glu(n), where n is the hydrocarbon chain length of 8, 10 and 12) has been studied on the basis of static/dynamic surface tension, fluorescence, dynamic light scattering (DLS) and cryogenic transmission electron microscope (cryo-TEM) data. The static surface tension of the aqueous Glu(n)-2-Glu(n) solutions measured at the critical micelle concentration (cmc) is observed to be significantly lower than that of the corresponding monomeric surfactants. This suggests that the gemini surfactants, newly synthesized in the current study, are able to form a closely packed monolayer film at the air/aqueous solution interface. The greater ability in the molecular association is supported by the remarkably (approximately 100-200 times) lower cmc of the gemini surfactants compared with the corresponding monomeric ones. With a combination of the fluorescence and DLS data, a structural transformation of the Glu(n)-2-Glu(n) micelles is suggested to occur with an increase in the concentration. The cryo-TEM measurements clearly confirm the formation of worm-like micelles of Glu(12)-2-Glu(12) at the concentration well above the cmc.     

Interactions of quaternary ammonium salt-type gemini surfactants with sodium poly(styrene sulfonate)

The interactions of cationic gemini surfactants, 1,2-bis(alkyldimethylammonio)ethane dibromide (m-2-m: m is hydrocarbon chain length, m = 10 and 12), and an anionic polymer, sodium poly(styrene sulfonate) (PSS), have been characterized by several techniques such as tensiometry, fluorescence spectroscopy, and dynamic light scattering. The surface tension of gemini surfactant/PSS mixed systems decreases with surfactant concentration, reaching break points, which are taken as critical aggregation concentrations (cac). The surface tension at the cac of mixtures is higher than that of single surfactants, and it is found that at concentrations above the cac, the surfactant molecules are associated with the polymer in the bulk. The 12-2-12/PSS mixed system shows higher surface activity than both 10-2-10/PSS and the monomeric surfactant of dodecyltrimethylammonium bromide/PSS systems. Fluorescence measurements of these mixed systems suggest the formation of a complex with a highly hydrophobic environment in the bulk of the solution. Additionally, dynamic light scattering measurements show that the hydrodynamic diameter of the 12-2-12/PSS mixed system is smaller than that of PSS only at low concentration, indicating interactions between surfactant and polymer. These result from the electrostatic attraction between ammonium and sulfate headgroups as well as the hydrophobic interaction between their hydrocarbon chains.     

Equilibrium and dynamic surface tension properties of partially fluorinated quaternary ammonium salt gemini surfactants

The equilibrium and dynamic surface tension properties of a partially fluorinated quaternary ammonium salt gemini surfactant 1,2-bis[dimethyl-(3-perfluoroalkyl-2-hydroxypropyl)ammonium]ethane bromide (C(n)(F)C3-2-C3C(n)F, where n represents fluorocarbon chain lengths of 4, 6, and 8) were investigated, and the effects of the fluorocarbon chain length and the number of chains on them were discussed. The plot of the logarithm of the critical micelle concentration (cmc) against the fluorocarbon chain length for C(n)(F)C3-2-C3C(n)F showed a linear decrease with an increase in chain length. On the basis of the slope of this plot, it was found that the variation in cmc with respect to the chain length is large for fluorinated gemini surfactants. The surface tension at the cmc decreased significantly; this surface tension value is lower than that of conventional fluorinated monomeric surfactants. In particular, the lowest value was 13.7 mN m(-1) for n = 8. Furthermore, it was confirmed that the kinetics of adsorption at the interface decrease with an increase in the fluorocarbon chain length and the concentration.     

Alkanediyl-alpha,omega-bis(dimethylalkylammonium bromide) surfactants 10. Behavior in aqueous solution at concentrations below the critical micellization concentration: an electrical conductivity study

Ion pairing and premicellar association have been often invoked to explain results obtained in studies of aqueous solutions of ionic dimeric surfactants (gemini surfactants), mainly by means of surface tension and electrical conductivity, at concentrations below the critical micellization concentration (cmc). The present work was undertaken in an attempt to find out under which conditions these effects come into play. For this purpose the electrical conductivity of solutions of many dimeric surfactants of the type spacer-alpha,omega-bis(alkyldimethylammonium bromide) have been measured. The alkyl chain contained m=10-18 carbon atoms. The spacer group was either an alkanediyl with s carbon atoms (m-s-m surfactants) or a xylylene m-xylyl-m surfactants). The results show that ion pairing occurs in solutions of m-s-m dimers with m< or =10, mostly as a result of their high cmc values. The results for 12-s-12 dimers with s< or =10 and for 12-xylyl-12 showed no evidence of either ion pairing or premicellar association. Premicellar association was present for 12-s-12 dimers with s> or =12, for m-8-m dimers with m> or =14, and for 16-xylyl-16. It showed through a positive curvature of the specific conductivity versus concentration plot and the presence of a maximum in the equivalent conductivity vs (concentration)(0.5) plot at concentrations below the cmc. The free energy associated with the premicellar association of m-8-m dimers has been estimated from the available cmc and micelle ionization degree data.     

Sugar-based gemini surfactants with peptide bonds-synthesis, adsorption, micellization, and biodegradability

The sugar-based gemini surfactant with peptide bonds, N,N'-bisalkyl-N,N'-bis[2-(lactobionylamide)ethyl]hexanediamide (2C(n)peLac, in which n represents hydrocarbon chain lengths of 12 and 16), was synthesized by reacting adipoyl chloride with the corresponding monomeric surfactant N-alkyl-N'-lactobionylethylenediamine (C(n)peLac), which was obtained by reacting ethylenediamine with alkyl bromide and lactobionic acid. The adsorption and micellization properties of C(n)peLac and 2C(n)peLac were characterized by the measurement of their equilibrium and dynamic surface tension, steady-state fluorescence using pyrene as a probe, dynamic light scattering (DLS), and time-resolved fluorescence quenching (TRFQ), and their biodegradability was also investigated. The critical micelle concentration (cmc) decreases with an increase in the hydrocarbon chains from monomeric to gemini surfactants, whereas it increases with an increase in the chain length from 12 to 16 for both systems. The increases in both the hydrocarbon chain and the chain length of sugar-based surfactants reduce surface activities such as the ability to lower the surface tension, the occupied area per molecule, and the adsorption rate at the air/water interface. The sugar-based surfactants C(n)peLac and 2C(n)peLac exhibit unique aggregation behavior in aqueous solution. The DLS results indicate that the apparent hydrodynamic diameter of C(n)peLac micelles decreases sharply with increasing concentration, whereas that of 2C(n)peLac micelles decreases gradually. From the TRFQ measurement, it was observed that, as concentration increases, the aggregation numbers are almost constant for C(n)peLac, whereas they increase for 2C(n)peLac. These results imply that loosely packed micelles formed by sugar-based surfactants become tightly packed micelles as the concentration increases. Furthermore, it was found that 2C(n)peLac shows lower biodegradability than does C(n)peLac because it contains tertiary amines in the molecule.     

Gemini表面活性剂烷烃尾链在吸附和聚集过程中的疏水协同效应(英文)

以表面张力法测定了系列Gemini表面活性剂m-6-m以及对应单体表面活性剂CmTABr的临界胶束浓度(cmc)和降低水表面张力20mN·m-1需要的浓度(pC20).比较这些参数表明m-6-m胶束化和在界面吸附的能力均强于CmTABr,这被归结为Gemini表面活性剂烷烃尾链间的疏水协同效应.与不对称Gemini表面活性剂12-6-m比较,对称的Gemini结构更有利于表面活性剂的聚集和吸附.     

pH-responsive surface activity and solubilization with novel pyrrolidone-based Gemini surfactants

A new series of pH-responsive Gemini surfactants with 2-pyrrolidone head groups, N,N'-dialkyl-N,N'-di(ethyl-2-pyrrolidone)ethylenediamine (Di-C(n)P, where n = 6, 8 10, 12), were synthesized and characterized by (1)H NMR, (13)C NMR, ESI-MS, and elemental analysis. The surface activity and micellization behavior at acidic, neutral, and basic conditions were characterized by equilibrium surface tension and fluorescence techniques. It was found that the surface activity of Di-C(n)P depends on the pH of aqueous solutions due to the protonation state of surfactant molecules when pH was varied. The new compounds have lower cmc and γ(cmc) in comparison with that of m-2-m type conventional cationic Gemini surfactants and gluconamide-type nonionic Gemini surfactants. Fluorescence data confirm that micelles are formed when the concentration is above the cmc. Since micellization is of fundamental importance in surfactant applications such as solubilization, microemulsion, and related technologies, the significant difference in cmc at different pH of this new Gemini surfactant is employed to solubilize cyclohexane. The preliminary result indeed shows that the solubilization capacity of Di-C(n)P can be tuned by pH.     

The unusual micelle micropolarity of partially fluorinated gemini surfactants sensed by pyrene fluorescence

New gemini surfactants having two fluorocarbon chains were prepared by refluxing partially fluorinated alkyl bromide with N,N,N',N'-tetramethyl-1,6-diaminohexane in acetonitrile. The partially fluorinated gemini surfactants containing a six-methylene spacer chain are easily soluble in water. The critical micelle concentrations (cmc's) were determined by various fluorescent probe methods. The hydrophobicity of a CF2 group was estimated to be 1.5 times that of a CH2 group according to the cmc values. The micelle micropolarity of a fluorocarbon gemini sensed by pyrene fluorescence was unusually high, suggesting an apparent iceberg-like environment in the location of pyrene. The significantly small micelle aggregation numbers of fluorinated gemini surfactants were ascertained by the pyrene fluorescence quenching method. The micelle ionization degree estimated by fluorescence quenching of 6-methoxy-N-(3-sulfopropyl)quinolinium (SPQ) gave tendencies similar to those of the corresponding hydrocarbon geminis.     

Shamrock surfactants: synthesis and characterization

Two types of a new class of surfactants with three headgroups, which possess the general structure 1, have been prepared. Within structure 1, a central headgroup is connected to two flanking headgroups by hydrocarbon chains. The term "shamrock" is used to describe surfactants of structure 1, denoting their triple-headed character and reflecting the fact that shamrocks have leaflets in groups of three. The major lipophilic character of shamrock surfactants is provided by the two hydrocarbon chains linking the three headgroups and not by long-chain alkyl groups appended to the linking hydrocarbon chains or the headgroups. The new surfactants are 2a (2,2,15,15,28,28-hexamethyl-2,15,28-triazonianonacosane triiodide), 2b (2,2,15,15,28,28-hexamethyl-2,15,28-triazonianonacosane trichloride), 3a (O,O'-di-[10-(N,N,N-tripropylammonio)decyl]phosphorodithioate bromide), and 3b (O,O'-di-[10-(N,N,N-tributylammonio)decyl]phosphorodithioate bromide). Compound 14 (2,2,9,9,16,16-hexamethyl-2,9,16-triazoniaheptadecane triiodide) was prepared for comparison with 2a. Surfactants 2 and 3 were characterized in water by measurement of their Krafft temperatures and critical aggregation concentrations, and their aggregates were studied by 1H NMR spectroscopy, dynamic laser light scattering, and phase-contrast optical microscopy. Aqueous 2b was also studied by cryo-etch high-resolution scanning electron microscopy, which revealed irregularly shaped cells containing a complex matrix of surfactant. Coacervates were observed by optical microscopy upon the hydration of 2 and 3.     

Interactions in mixed cationic surfactants and dextran sulfate aqueous solutions

The interactions between a hydrophilic anionic polysaccharide, dextran sulfate, and oppositely charged surfactants, n-alkylammonium chlorides (the number of carbon atoms per chain being 10, 12, and 14), were investigated by optical microscopy, X-ray diffraction, microelectrophoretic mobility, conductivity, surface tension, and light-scattering measurements at 303 K. The increase of surfactant alkyl chain length shifts both the critical aggregation (cac) and the critical micelle concentrations (cmc) toward lower surfactant concentration. Light-scattering and microelectrophoretic data revealed the coexistence of differently structured complexes beyond the cac. The presence of giant vesicles indicates that at least one type of species is ordered in bilayers. X-ray analysis of dry n-alkylammonium dextran sulfates exhibited mesomorphous ordering and interplanar spacings typical for lamellar structures; i.e., n-alkylammonium molecules form more or less disordered bilayers interconnected with dextran sulfate chains, thus forming multilamellar stacks. The average basic lamellar thickness increased linearly with the increase of surfactant chain length, whereas the average number of lamellar bilayers in the stack of lamellae decreases.     

Synthesis and Properties of Aromatic Side Chained N‐Acyltaurate Surfactants

A series of anionic N‐acyltaurate surfactants, side chain containing aromatic nucleus (abbreviated as SAATT), were synthesized via Williamson reaction, hydrolyzation, and acylation. Krafft temperatures and surface properties of these surfactants at 30°C, that is, critical micelle concentration, cmc, surface excess concentration, Γ_max, surface area demand per molecule, A _min, efficiency in surface tension reduction, pC₂₀, effectiveness in surface tension reduction, π_cmc, and cmc/C₂₀ parameter were determined. It was shown that these surfactants exhibit good solubility which was confirmed by measuring Krafft temperature. The cmc of SAATT was much smaller than that of conventional surfactants with similar effective carbon numbers, and shifted to lower concentration with increasing hydrocarbon chain length. In addition, the γ_cmc decreased with decrease in Γ_max. The pC₂₀ and the cmc/C₂₀ got larger with the increase in hydrocarbon chain length. From the fluorescence intensity ratios of I ₁ (373 nm) and I ₃ (384 nm) using pyrene as a probe, it was indicated that the molecules of SAATT formed loose micelles with a broad size distribution.     

Adsorption and Micellization Properties of Novel Heterodouble‐Chained N‐Acyltaurate Surfactants

A set of heterodouble‐chained N‐acyltaurate surfactants (abbreviated as m+nP‐T, where m and n were carbon numbers of alkyl chain; P was phenyl; T was taurate) were synthesized. The novel amphiphiles contained sodium taurine as hydrophilic moiety and two different hydrocarbon chains as hydrophobic moiety. One was a long alkyl chain, and the other had an aromatic residue. Their surface properties were determined by Wilhelmy‐plate method, and micellization properties were investigated by fluorescence spectra of extrinsic probe and intrinsic probe. It was found that these surfactants showed some aberrant properties. It was difficult to obtain the equilibrium surface tension and critical micelle concentration (cmc) for the surfactants with two long chains. Pyrene was solubilized in micelle at concentration above cmc, and the fluorescent intensity ratio of the first vibronic peak (373 nm) to the third vibronic peak (383 nm) of pyrene decreased gradually. The aggregation number N, characterized by quenching the phenoxyl residue with methyl viologen (MV²⁺) as the extrinsic quencher, gradually increased with increasing surfactant concentration. These indicated that more and more molecules packed in a micelle with increasing concentration.     

Micellization of dissymmetric cationic gemini surfactants and their interaction with dimyristoylphosphatidylcholine vesicles

The micellization process of a series of dissymmetric cationic gemini surfactants [CmH2m+1(CH3)2N(CH2)6N(CH3)2C6H13]Br2 (designated as m-6-6 with m = 12, 14, and 16) and their interaction with dimyristoylphosphatidylcholine (DMPC) vesicles have been investigated. In the micellization process of these gemini surfactants themselves, critical micelle concentration (cmc), micelle ionization degree, and enthalpies of micellization (DeltaHmic) were determined, from which Gibbs free energies of micellization (DeltaGmic) and entropy of micellization (DeltaSmic) were derived. These properties were found to be influenced significantly by the dissymmetry in the surfactant structures. The phase diagrams for the solubilization of DMPC vesicles by the gemini surfactants were constructed from calorimetric results combining with the results of turbidity and dynamic light scattering. The effective surfactant to lipid ratios in the mixed aggregates at saturation (Resat) and solubilization (Resol) were derived. For the solubilization of DMPC vesicles, symmetric 12-6-12 is more effective than corresponding single-chain surfactant DTAB, whereas the dissymmetric m-6-6 series are more effective than symmetric 12-6-12, and 16-6-6 is the most effective. The chain length mismatch between DMPC and the gemini surfactants may be responsible for the different Re values. The transfer enthalpy per mole of surfactant within the coexistence range may be associated with the total hydrophobicity of the alkyl chains of gemini surfactants. The transfer enthalpies of surfactant from micelles to bilayers are always endothermic due to the dehydration of headgroups and the disordering of lipid acyl chain packing during the vesicle solubilization.     

Mixed micelles containing sodium oleate: the effect of the chain length and the polar head group

We have investigated the mixing behavior of binary mixtures of the alkylglucosides (CnG) octyl beta-D-glucoside and decyl D-glucoside in combination with sodium oleate (NaOl), and the amine oxide surfactants (AO) N,N-dimethyldodecylamine oxide, N,N-bis (2-hydroxyethyl)dodecylamine oxide, and 3-lauramidopropyl-N,N-dimethylamine oxide in combination with NaOl. From the equilibrium surface tension measurements, the critical micelle concentration (cmc) data were obtained as functions of the composition. Values of the cmc were analyzed according to both the regular solution model developed by Rubingh for mixed micelles and Maeda's formulation for ionic/nonionic mixed micelles. Two interaction parameters, beta and B1, were estimated from the regular solution model and Maeda's formulation, respectively. For NaOl/CnG mixed systems, a decrease in the hydrocarbon chain length of CnG resulted in a stronger interaction with NaOl from both beta and B1 values. For NaOl/AO mixed systems, the bulkiness of a polar head group of AO surfactants influenced the interaction between NaOl and AO. The dynamic surface tension measurements show that all surface tension values of surfactant solutions examined decreased with the time. We found that the time dependence of surface tension values for NaOl mixed systems was greatly influenced by the presence of NaOl rather than the other component.