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.     

Physicochemical properties of quaternized poly(amidoamine) dendrimers with alkyl groups and of their mixtures with sodium dodecyl sulfate

The physicochemical properties of quaternized poly(amidoamine) dendrimers (generation 4) with methyl or octyl groups and of their mixtures with sodium dodecyl sulfate (SDS) in aqueous solutions have been investigated using several techniques including surface tension, fluorescence of pyrene, and dynamic light scattering. In the single systems of the dendrimers, the dendrimer with octyl groups shows lower surface tension and lower micropolarity than the dendrimer with methyl groups. The hydrodynamic radii of two quaternized poly(amidoamine) dendrimers are considerably large, indicating the formation of aggregates. In the mixed systems of quaternized poly(amidoamine) dendrimers and SDS, the dendrimer with octyl groups-SDS mixed system shows very low surface tension and low micropolarity even in the presence of extremely low SDS concentration compared to those of the dendrimer with methyl groups-SDS mixed system. Maximum turbidity for both systems is observed at around the mixed molar ratio of dendrimer:SDS=1:1.5 where distinct changes have also been confirmed by surface tension, fluorescence of pyrene, and electrical conductivity measurements.     

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.     

Interaction between zwitterionic and anionic surfactants: spontaneous formation of zwitanionic vesicles

The physicochemical properties, such as critical micelle concentration (cmc), surface tension at cmc (γ(cmc)), and surface activity parameters of the mixtures of a new amino acid-based zwitterionic surfactant, N-(n-dodecyl-2-aminoethanoyl)-glycine (C(12)Gly) and an anionic surfactant, sodium dodecyl sulfate (SDS) at different molar fractions, X(1) (= [C(12)Gly]/([C(12)Gly] + [SDS])) of C(12)Gly were studied. A synergistic interaction was observed between the surfactants in mixtures of different X(1). The self-organization of the mixtures at different molar fractions, concentrations, and pH was investigated. Fluorescence depolarization studies in combination with dynamic light scattering, and transmission electron microscopic and confocal fluorescence microscopic images suggested the formation of bilayer vesicles in dilute solutions of SDS rich mixtures with X(1) ≤ 0.17 in the pH range 7.0 to 9.0. However, the electronic micrographs showed structures with fingerprint-like texture in moderately dilute to concentrated C(12)Gly/SDS mixture at X(1) = 0.50. The vesicles were observed to transform into small micelles upon lowering the solution pH and upon increase of total surfactant concentration in mixtures with X(1) ≤ 0.17. However, decrease of SDS content transformed vesicles into wormlike micelles. The structural transitions were correlated with bulk viscosity of the binary mixtures.     

Physicochemical properties of quaternary ammonium bromide-type trimeric surfactants

Trimeric surfactants of quaternary ammonium bromide (m-2-m-2-m, where m is the hydrocarbon chain length of 8, 10, or 12) with three hydrocarbon chains and three hydrophilic groups connected by two ethylene spacer chains were synthesized by the reaction of N,N,N',N",N"-pentamethyldiethylenetriamine and the corresponding alkyl bromide. Their physicochemical properties were characterized by surface tension, static and dynamic light-scattering, and fluorescence spectrum of pyrene techniques. The critical micelle concentrations (cmc's) of m-2-m-2-m shifted to lower concentrations with increasing hydrocarbon chain length, and their values were smaller by about one to three orders of magnitude than those of the corresponding dimeric (m-2-m) and monomeric surfactants (C(m)TAB) with the same hydrocarbon chain length. Of these surfactants, 10-2-10-2-10 showed the greatest efficiency in lowering the surface tension and provided the smallest occupied area per molecule, indicating that it adsorbs more compactly at the air/water interface. In addition, from the static and dynamic light-scattering measurements, the aggregation numbers of the trimeric surfactants at the cmc were very small, and two hydrodynamic diameters above the cmc were observed.     

Direct force measurements between adlayers consisting of poly(amidoamine) dendrimers with primary amino groups or quaternary ammonium groups

Adsorption of poly(amidoamine) generation 3 (PAMAM G3) dendrimer with surface amino groups or PAMAM G0 dendrimer with quaternary ammonium groups (C8qbG0) onto glass has been studied by colloidal probe atomic force microscopy. The adlayer-adlayer interactions for these adsorbates are quite different despite the fact that they are almost equal in the hydrodynamic radius. In aqueous PAMAM G3 dendrimer solutions the electrostatic repulsion is predominant. The conformation of the adsorbed layer is flat and the protrusion of the individual dendrimers is negligible. On the other hand, C8qbG0 behaves as a surfactant and the layered structure of C8qbG0 is expected to be a patchy bilayer. Dispersion stability of silica suspensions with the adsorption of these dendrimers can be correlated with the force data obtained.     

全氟丁基磺酸钠与辛基三乙基溴化铵的相互作用

通过测定辛基三乙基溴化铵(C8H17N(CH2CH3)3Br,C8NE)与全氟丁基磺酸钠(C4F9SO3Na,C4F)组成的不同混合比的碳氢-碳氟正负离子表面活性剂混合体系的表面张力,得到不同摩尔比时C8NEC4F体系的临界胶束浓度(cmc)、cmc处的表面张力(γcmc)、总饱和吸附量、不同表面张力时表面吸附层的组成,利用Gibbs-Duhem方程求得cmc处的胶团组成。 采用规则溶液理论计算了胶团中分子间相互作用参数(βm),并求得cmc以上的胶团组成。 实验表明,C8NEC4F复配体系的cmc远远小于单体系的cmc,这也体现在该体系的βm负值很大,胶团内分子相互作用很强。 但是C4F与C8NE复配后γcmc较C4F单体系的变化幅度不是特别大(γcmc降低2~4 mN/m),这是由于C8NEC4F碳链的不对称性导致部分C8NE的碳链在溶液表面弯曲而覆盖了C4F端基CF3基团。 表面吸附层中氟表面活性剂相对于本体溶液是富集的,即使对于C8NE大大过量的体系,表面吸附层组成也在等摩尔附近;对于C4F过量的体系,C4F在表面吸附层中的比例比溶液中的略高。 随着表面张力的降低,表面吸附层的组成相对更偏向于氟表面活性剂。 cmc处的胶团组成随着体系中C4F含量的增大偏向于形成显著富含C4F的胶团,对于C8NE大大过量的体系,胶团组成接近等摩尔。 cmc之后的胶团组成接近等摩尔,主要归因于此时静电相互作用占主导,这和溶液配制过程中发现复配体系超过cmc一定浓度后就易生成沉淀的现象是相符的。     

Aggregation and adsorption properties of sodium dodecyl sulfate in water-acetamide mixtures

The critical micelle concentration (cmc) of sodium dodecyl sulfate was determined in water + acetamide media from 0 to 70 wt% of acetamide and at temperatures in the range from 20 to 40 degrees C by using conductance, surface tension, and fluorescence methods. The cmc increases with increase in acetamide concentration and the reported [M.S. Akhter, Colloids Surf. A 121 (1997) 103] decrease in cmc was not observed. The limiting surface tension at the cmc does not have any dependence on the amount of acetamide added. The cmc data as a function of temperature were used to estimate the free energy, enthalpy, and entropy terms for micellization. Enthalpy-entropy compensation takes place during micellization. Counterion binding constant, surface excess, and aggregation number of SDS decrease with increasing acetamide concentration and become almost constant for weight percentages of acetamide greater or equal to 30. Pyrene appears to move from the interior of the SDS micelle to the micellar interface at about 30 wt% acetamide. The empirical relations reported by Aguiar et al. [J. Aguiar, P. Carpena, J.A. Molina-Bolivar, C. Carnero Ruiz, J. Colloid Interface Sci. 258 (2003) 116] between the parameters of a sigmoid-type expression for the ratio of fluorescence emission intensities of pyrene and surfactant properties are found to be applicable to SDS in water + acetamide medium below 20 wt% acetamide only. Standard free energy of micellization has linear correlations with reciprocal of dielectric constant and Gordon parameter of the solvent. The water + acetamide medium behaves similar to mixed solvents containing water and any polar liquid nonaqueous solvent and this study highlights the significance of solvophobicity.     

Pyrene fluorescence at air/sodium dodecyl sulfate solution interface

The dependence of pyrene fluorescence spectra on the concentration of sodium dodecyl sulfate (SDS) was observed, where the solution was prepared from water saturated with pyrene. The values of the I(1)/I(3) ratio from the bulk solution and from the upper meniscus region in an optical cell were similar but decreased rapidly around the critical micelle concentration (cmc) of SDS, indicating that pyrene molecules preferred to be solubilized in the micelles having a lower dielectric constant. The fluorescence intensity of the excimer indicated the concentration of pyrene molecules at the air/solution interface or the surface activity of pyrene molecules. In addition, the intensity from the meniscus region is much larger than that from the bulk at the concentrations below the cmc, whereas there was no difference in the intensity between the bulk and the meniscus above 8 mmol dm(-3) of SDS. The analysis of the fluorescence intensity from the excimer strongly suggests the presence of molecular aggregates that are favorable to the pyrene molecules just like the micelles in the bulk, making them less movable.     

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.     

Studies on bovine serum albumin-sodium dodecyl sulfate complexes using pyrene fluorescence probe and 5-doxylstearic acid spin probe

Interactions and characteristics of 0.1% bovine serum albumin (BSA)-sodium dodecyl sulfate (SDS) in 20 mM phosphate buffer solution were investigated by means of fluorescence spectroscopy and electron spin resonance (ESR) spectroscopy. In BSA-SDS system, the intensity ratio, Im3/Im1, of the third vibronic band of the pyrene monomer to the first vibronic band showed a small peak at about 0.1 mM SDS in the phosphate buffer below cmc. In accordance with this Im3/Im1 ratio, the intensity ratio, Ie/Im1, of fluorescence from the pyrene excimer to that from the monomer showed a pseudo-plateau (0.08-0.8 mM) and suggested the existence of micelle-like aggregates below the cmc. Temperature dependence of ln(Ie/Im1) in pyrene fluorescence in the SDS-BSA system was examined as a function of SDS concentration. The activation energy of pyrene diffusion for excimer formation in a micelle was estimated to be 19.2 kJ mol(-1) for the BSA-SDS system. ESR spectra of 5-doxylstearic acid (5-DSA) showed that the probe location is restricted at SDS concentrations above the cmc, and that the probe also is highly restricted in motion for BSA-bound SDS micelles.     

Solubilization study for aggregates of sodium dodecyl sulfate and cationic polymer of high charge density

Interaction of sodium dodecyl sulfate (SDS) with a cationic polymer (polydiallyldimethylammonium chloride, PDADMAC) was investigated. The surface tension of SDS/PDADMAC solution ([PDADMAC]=100 ppm) decreased from 72 to ca. 40 mN m(-1) with increasing SDS concentration at 298.2 K, where the SDS concentration, 0.6 mmol dm(-3), at 40 mN m(-1) was less than cmc/10 of SDS. From the relatively high value of I1/I3, ca. 1.5, in the pyrene fluorescence spectrum, which is larger than the value in SDS micelles, the aggregation number is suggested to be lower than that of SDS micelles. The maximum additive concentration for n-alkylbenzenes as solubilizate increased with the increase in SDS concentration and with decreasing alkyl chain length of the solubilizates. The Gibbs energy changes for their solubilization from the phase separation model were almost the same as those from the mass action model for longer chain solubilizates, due to their smaller solubilized amounts in the micelles. The Gibbs energy change for the solubilization decreased with increasing alkyl chain length of the solubilizates. The Gibbs energy decrease per CH2 group (deltaG(CH2)0) was larger in magnitude than for micelles of single-surfactant systems, which was substantiated by the absorption spectrum change of the solubilizates.     

聚丙烯酸接枝辛基酚聚氧乙烯醚的合成、表征和胶束化

通过自由基聚合, 丙烯酸(AA)与辛基酚聚氧乙烯醚丙烯酸酯活性大单体(C8PhEO10Ac)共聚,合成了以聚丙烯酸为主链、C8PhEO10Ac 为支链的水溶性两亲接枝共聚物(PAA-g-C8PhEO10Ac), 用凝胶渗透色谱(GPC)测定其相对数均分子质量为4.37×10⁴, 用FTIR和1H-NMR表征了共聚物的结构和组成, 共聚物分子中丙烯酸单体与活性大单体的摩尔比为9:1, 每个共聚物分子中平均约有32个C8PhEO10侧链. 用表面张力法、荧光探针法和透射电子显微镜对共聚物在水溶液中的自组装行为进行了初步研究, 结果表明, 共聚物分子在第一临界胶束浓度cmc1)和第二临界胶束浓度(cmc2)时都形成了球型胶束. 与cmc1时相比, cmc2时溶液表面张力进一步降低, 胶束内部极性进一步减小, 而且胶束粒径增大、结构紧密. 氯化钠的加入可使共聚物溶液的表面张力和胶束内部极性降低.     

荧光探针法测定甜菜碱cmc的研究

荧光探针法测定甜菜碱ｃｍｃ的研究任学贞，李干佐，王弘立，翟立民，隋卫平，徐欣艳（山东大学化学系，济南，２５０１００）关键词甜菜碱，芘，临界胶束浓度Ｅｋｗａｌｌ等［１］发现，表面活性剂的溶液能够增溶多环芳烃并发射较强的荧光．在常用的测定表面活性剂临界胶...     

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.     

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.     

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.     

Micelle formation of Tyr-Phe dipeptide and Val-Tyr-Val tripeptide in aqueous solution and their influence on the aggregation of SDS and PEO-PPO-PEO copolymer micelles

The aggregation properties of Tyr-Phe dipeptide and Val-Tyr-Val tripeptide were studied in aqueous solution and in the presence of SDS and SDS-polymer environments using UV-visible, surface tension, fluorescence and circular dichroism (CD) techniques. Both the peptides formed micelles. The cmc values obtained for dipeptide and tripeptide are 2×10(-5) and 4×10(-5) M, respectively in aqueous solution at 25°C. The presence of additives (SDS and polymer) hindered the micelle formation of peptides. The cmc values obtained by various methods are in good agreement with each other. Effect of peptides on the aggregation properties of SDS also was investigated. The cmc of SDS was decreased in presence of peptides and were reduced with increase in temperature. Using monophasic micellization concept, the association constant (K(A)) for the SDS-peptide mixed micellar systems was determined. Using biphasic model, the thermodynamic parameters viz; ΔG°(m), ΔH°(m) and ΔS°(m) for SDS-water and SDS-peptide-water mixed micellar systems, the standard free energy for transfer of SDS from aqueous to peptide additive environments were estimated at various temperatures. These results suggest that the SDS is more stable in micellized form in the SDS-water-peptide ternary systems compared to the situation in the corresponding SDS-water binary systems.     

The aggregation of the sodium dodecyl sulfate –n - octanol–water system at low concentration

Micelle formation in sodium dodecyl sulfate (SDS)–n-octanol mixtures was studied by several techniques and the results were interpreted using regular solution theory for mixed-micelle formation. Octanol was considered as a nonionic surfactant. The composition of micelles at the critical micelle concentration (cmc) was computed together with the interaction parameter and the activity coefficient of the components of the micelles. The fluorescence quenching technique with pyrene was employed to obtain the SDS and octanol aggregation numbers at the cmc. The results were in agreement with similar studies on other alcohol–SDS systems. At the cmc spherical, almost fully ionized micelles formed, while at a higher concentration there was a transition to anisometric (probably rodlike) micelles which pushed sodium counterions into their Stern double layer. Mixed anisometric micelles were more ionized than pure SDS micelles. When the octanol:SDS total ratio exceeded 0.85:1, an emulsion of octanol appeared in equilibrium with the micelles. Received: 23 December 1998 Accepted in revised form: 3 March 1999     

全氟壬烯氧基苯磺酸钠与烷基季铵盐的相互作用

通过六氟丙烯三聚体(全氟壬烯)氧基苯磺酸钠(C₉F₁₇OC₆H₄SO₃Na, OBS)与阳离子碳氢表面活性剂C_nNR[C_nH_2n+1N(CH₃)₃Br, C_nNM, n=8, 10和C_nH_2n+1N(CH₂CH₃)₃Br, C_nNE, n=8, 10, 12]复配, 研究了OBS与C_nNR的摩尔比、 C_nNR疏水链长及C_nNR亲水基团大小对此类阴、 阳离子碳氟-碳氢表面活性剂混合体系的临界胶束浓度(cmc)、 最低表面张力(γ_cmc)、 总饱和吸附量(Γ_tm)及极限分子面积(A_min)的影响. 结果表明, 通过与C_nNR复配, OBS的cmc和γ_cmc均大幅下降, 达到了全面增效的结果. 不同摩尔比的OBS-C₈NE混合体系中, 摩尔比为1:1时表面活性最好, cmc和γ_cmc均最小; 偏离等摩尔比时, OBS过量时混合体系的cmc小于C₈NE过量时混合体系的cmc, 但γ_cmc相差不大. 与单体系相比, OBS-C₈NE混合体系的Γ_tm明显增大、 A_min明显变小. OBS与不同疏水链长的C_nNE复配时, cmc的变化规律为C₈NE>C₁₀NE>C₁₂NE, 表明C_nNE疏水链长的增加能降低混合体系的cmc. 通过比较C_nNM和C_nNE(n=8, 10)的表面活性发现, 改变混合体系中C_nNR的亲水基团大小对混合体系的表面活性无明显影响.