Self-consistent field modeling of linear nonionic micelles

A self-consistent field theory is used to predict structural, mechanical, and thermodynamical properties of linear micelles of selected nonionic surfactants of the type C(n)()E(m). Upon increase in surfactant concentration the sudden micelle shape transition from spherical to cylindrical (second critical micelle concentration (cmc)) is analyzed. The cylindrical micelles consist of a body (with radius R(c) and length L) and two slightly swollen endcaps. For small L, the shape resembles a dumbbell. With increase in the length of the body, an oscillatory behavior in the grand potential of the micelle is found. The wavelength of the oscillation (lambda(d)) is proportional to the surfactant tail length n. The amplitude of these oscillations decreases exponentially with a decay length xi. In the limit of very long micelles, the grand potential converges to the endcap (free) energy E(c). This endcap energy increases approximately quadratic with the tail length and diminishes by increasing the headgroup size m. The micelle size distribution is generated showing non-monotonic features due to the presence of short dumbbells and becomes exponential when L > 8R(c). It is also shown that the endcap energy can be estimated in first order by the grand potential of the spherical micelle that coexists with infinitely long cylindrical micelles. The persistence length l(p) of these linear micelles is evaluated to estimate the relative importance of conformational entropy for these micelles.     

Toluene solubilization induces different modes of mixed micelle growth

The effect of toluene solubilization on the size and mobility of Triton X100 (TX100) micelles and TX100/sodium dodecyl sulfate (SDS) mixed micelles was studied by turbidimetry, dynamic light scattering, and capillary electrophoresis. Micelle growth due to toluene solubilization was observed for both surfactant systems; however, two different modes of growth were seen. Mixed micelles in 0.1 M NaCl are spherical (apparent diameter d(app) = 8 nm) and remain so while taking up 3 mM toluene, with a volume increase per micelle of deltaV(m) = 50 nm3. In 0.5 M NaCl, the large d(app) of both nonionic and mixed micelles (14 and 24 nm, respectively) indicate ellipsoidal or rodlike shapes, and their large increases in d(app) upon addition of 3 mM toluene thus correspond to elongational growth, with the same deltaV(m) = 50 nm3. Further addition of toluene to TX100/SDS in 0.5 M NaCl results in a dramatic increase in micelle size followed by an unexpected bimodal size distribution. The addition of excess toluene leads to the formation of ca. 140 nm toluene droplets, stabilized mainly by monomers of the high critical micelle concentration surfactant, SDS. These microemulsions coexist with the smaller (20 nm) swollen mixed micelles.     

Synergistic sphere-to-rod micelle transition in mixed solutions of sodium dodecyl sulfate and cocoamidopropyl betaine

Static and dynamic light scattering experiments show that the mixed micelles of sodium dodecyl sulfate (SDS) and cocoamidopropyl betaine (CAPB) undergo a sphere-to-rod transition at unexpectedly low total surfactant concentrations, about 10 mM. The lowest transition concentration is observed at molar fraction 0.8 of CAPB in the surfactant mixture. The transition brings about a sharp increase in the viscosity of the respective surfactant solutions due to the growth of rodlike micelles. Parallel experiments with mixed solutions of CAPB and sodium laureth sulfate (sodium dodecyl-trioxyethylene sulfate, SDP3S) showed that the sphere-to-rod transition in SDP3S/CAPB mixtures occurs at higher surfactant concentrations, above 40 mM. The observed difference in the transition concentrations for SDS and SDP3S can be explained by the bulkier SDP3S headgroup. The latter should lead to larger mean area per molecule in the micelles containing SDP3S and, hence, to smaller spontaneous radius of curvature of the micelles (i.e., less favored transition from spherical to rodlike micelles). The static light scattering data are used to determine the mean aggregation number and the effective size of the spherical mixed SDS/CAPB micelles. From the dependence of the aggregation number on the surfactant concentration, the mean energy for transfer of a surfactant molecule from a spherical into a rodlike micelle is estimated.     

Characterization of Surfactant-Diblock Copolymer Interactions and Its Thermodynamic Studies

The interaction of nonionic diblock copolymer poly(ethylene oxide butylene oxide) (E₆₂B₂₂) with a cationic surfactant cetyl trimethyl ammonium bromide (CTAB) and anionic surfactant sodium dodecyl sulphate (SDS) were studied using surface tension, conductivity, and dynamic laser light scattering techniques. Surface tension measurements were used to determine critical micelle concentration and thereby its free energy of adsorption (ΔG_ads), free energy of micellization (ΔG_m), surface excess concentration (Γ), and minimum area per molecule (A). Conductivity measurements were used to determine critical micelle concentration (CMC) critical aggregation concentration (CAC) at different temperatures, enthalpy of micellization (ΔH_m), free energy of micellization and entropy of micellization (ΔS_m). Changes in physicochemical properties of the micellized block copolymer were studied by using dynamic laser light scattering. The effect of surfactant on the size and properties of block copolymer has also been discussed.     

Structure of mixed anionic/nonionic surfactant micelles: experimental observations relating to the role of headgroup electrostatic and steric effects and the effects of added electrolyte

The structures of the mixed anionic/nonionic surfactant micelles of SDS/C12E6 and SDS/C12E8 have been measured by small angle neutron scattering (SANS). The variations in the micelle aggregation number and surface charge with composition, measured in D2O and in dilute electrolyte, 0.01 and 0.05 M NaCl, provide data on the relative roles of the surfactant headgroup steric and electrostatic interactions and their contributions to the free energy of micellization. For the SDS/C12E8 mixture, solutions increasingly rich in C12E8 show a modest micellar growth and an increase in the surface charge. The changes with increasing electrolyte concentration are similarly modest. In contrast, for the SDS/C12E6 mixture, solutions rich in C12E6 show a more significant increase in aggregation number. Furthermore, electrolyte has a more substantial effect on the aggregation for the nonionic (C12E6) rich mixtures. The experimental results are discussed in the context of estimates of the steric and electrostatic contributions to the free energy of micellization, calculated from the molecular thermodynamic approach. The variation in micelle surface charge is discussed in the context of the "dressed micelle" theory for micelle ionization, and other related data.     

Foam films in the presence of functionalized gold nanoparticles

Dry aqueous foams made of anionic surfactant (SDS) and spherical gold nanoparticles are studied by small angle X-ray scattering and by optical techniques. To obtain stable foams, the surfactant concentration is well above the critical micelle concentration. The specular reflectivity signal obtained on a very thin film (thickness 20 nm) shows that functionalized nanoparticles (17 nm typical size) are trapped within the film in the form of a single monolayer. In order to isolate the film behavior, investigations are made on a single film confined in a tube. The film thinning according to the ratio of functionalized nanoparticle and SDS micelles (1:1, 1:10, 1:100) is mainly governed by the structural arrangement of SDS micelles. In thick films, nanoparticles tend to form aggregates that disappear during drainage. In particular self-organization of nanoparticles (with different surface charge) inside the film is not detected.     

Interaction between a partially fluorinated alkyl sulfate and gelatin in aqueous solution

The interaction of a partially fluorinated alkyl sulfate, sodium 1H,1H,2H,2H-perfluorooctyl sulfate (C6F13CH2CH2OSO3Na), with the polyampholyte gelatin has been examined in aqueous solution using surface tension and small-angle neutron scattering (SANS). The 19F chemical shift of each fluorine environment in the surfactant is unaltered by the addition of gelatin, indicating that there is no contact between the gelatin and the fluorocarbon core of the micelle. The chemical shift of the two methylene groups closest to the headgroup is altered when gelatin is present, disclosing the location of the polymer. The critical micelle concentration (cmc) of the surfactant, cmc = 17+/-1 mM, corresponds to an effective alkyl chain (CnH2n+1) length of n = 11. In the presence of gelatin, the cmc is substantially reduced as expected, cmc(1) = 4+/-1 mM, which is also consistent with an effective alkyl chain length of n = 11. In the presence of the fluorosurfactant, the monotonic decay of the SANS from the gelatin-only system is replaced by a substantial peak at an intermediate Q value mirroring the micellar interaction. At low ionic strengths, the gelatin/micelle complex can be described by an ellipsoid. At higher ionic strengths, the electrostatic interaction between the micelles is screened and the peak in the gelatin scattering disappears. The correlation length describing the network structure decreases with increasing SDS concentration as the bound micelles promote a collapse of the network.     

Interactions of Ionic Surfactants With PEO-PBO-PEO Triblock Copolymers in Aqueous Solutions

The interactions of triblock copolymers (TBP) with ionic surfactants were studied employing surface tensiometry, electrical conductivity, steady-state fluorescence (SSF), and dynamic light scattering (DLS) techniques. An increasing trend in the critical micelle concentration (CMC) of SDS/CTAB in the presence of triblock copolymers was observed especially at higher polymer to surfactant ratio. The delay in the CMC of surfactants was more pronounced in the presence of E₄₈B₁₀E₄₈ possibly due to its less hydrophobic nature. The negative values of free energy of micellization (ΔG_m) both in case of SDS and CTAB confirmed the spontaneity of the processes. The aggregation number (N_agg) and hydrodynamic radius (R_h) of polymer/surfactant mixed systems were determined by SSF and DLS. The suppression of the surfactant micelle size in the presence of TBP was confirmed by SSF and DLS studies.     

Spectrophotometric study of interaction and solubilization of procaine hydrochloride in micellar systems

The interaction of Procaine hydrochloride (PC) with cationic, anionic and non-ionic surfactants; cetyltrimethylammonium bromide (CTAB), sodium dodecyl sulfate (SDS) and triton X-100, were investigated. The effect of ionic and non-ionic micelles on solubilization of Procaine in aqueous micellar solution of SDS, CTAB and triton X-100 were studied at pH 6.8 and 29°C using absorption spectrophotometry. By using pseudo-phase model, the partition coefficient between the bulk water and micelles, K_x, was calculated. The results showed that the micelles of CTAB enhanced the solubility of Procaine higher than SDS micelles (K_x = 96 and 166 for SDS and CTAB micelles, respectively) but triton X-100 did not enhanced the solubility of drug because of weak interaction with Procaine. From the resulting binding constant for Procaine-ionic surfactants interactions (K_b = 175 and 128 for SDS and CTAB surfactants, respectively), it was concluded that both electrostatic and hydrophobic interactions affect the interaction of surfactants with cationic procaine. Electrostatic interactions have a great role in the binding and consequently distribution of Procaine in micelle/water phases. These interactions for anionic surfactant (SDS) are higher than for cationic surfactant (CTAB). Gibbs free energy of binding and distribution of procaine between the bulk water and studied surfactant micelles were calculated.      

Structural organization of cetyltrimethylammonium sulfate in aqueous solution: The effect of Na2SO4

We used dynamic light scattering (DLS), steady-state fluorescence, time resolved fluorescence quenching (TRFQ), tensiometry, conductimetry, and isothermal titration calorimetry (ITC) to investigate the self-assembly of the cationic surfactant cetyltrimethylammonium sulfate (CTAS) in aqueous solution, which has SO(2-)4 as divalent counterion. We obtained the critical micelle concentration (cmc), aggregation number (N(agg)), area per monomer (a0), hydrodynamic radius (R(H)), and degree of counterion dissociation (alpha) of CTAS micelles in the absence and presence of up to 1 M Na2SO4 and at temperatures of 25 and 40 degrees C. Between 0.01 and 0.3 M salt the hydrodynamic radius of CTAS micelle R(H) approximately 16 A is roughly independent on Na2SO4 concentration; below and above this concentration range R(H) increases steeply with the salt concentration, indicating micelle structure transition, from spherical to rod-like structures. R(H) increases only slightly as temperature increases from 25 to 40 degrees C, and the cmc decreases initially very steeply with Na2SO4 concentration up to about 10 mM, and thereafter it is constant. The area per surfactant at the water/air interface, a0, initially increases steeply with Na2SO4 concentration, and then decreases above ca. 10 mM. Conductimetry gives alpha = 0.18 for the degree of counterion dissociation, and N(agg) obtained by fluorescence methods increases with surfactant concentration but it is roughly independent of up to 80 mM salt. The ITC data yield cmc of 0.22 mM in water, and the calculated enthalpy change of micelle formation, Delta H(mic) = 3.8 kJ mol(-1), Gibbs free energy of micellization of surfactant molecules, Delta G(mic) = -38.0 kJ mol(-1) and entropy TDelta S(mic) = 41.7 kJ mol(-1) indicate that the formation of CTAS micelles is entropy-driven.     

Effects of surfactant and temperature on rheological and structural properties of semidilute aqueous solutions of unmodified and hydrophobically modified alginate

The dynamic and structural perturbations that result from the interactions between the anionic surfactant sodium dodecyl sulfate (SDS) and the hydrophobically modified biopolymer alginate (HM-alginate) have been studied with the aid of rheological methods, turbidimetry, and small-angle neutron scattering (SANS). The rheological results for a semidilute HM-alginate solution in the presence of SDS disclose strong interactions between HM-alginate and SDS at a low level of surfactant addition, and this feature is accompanied by enhanced turbidity. At higher surfactant concentrations the association complexes are disrupted. A strong temperature effect of the viscosity is observed in HM-alginate solutions at moderate SDS concentrations, where an elevated temperature leads to enhanced chain mobility, which promotes a breakup of the association complexes. The SANS results reveal a pronounced peak in the plot of scattered intensity versus wavevector q at intermediate q values for SDS concentrations above the critical micelle concentration (cmc). With contrast-matching conditions, using deuterated SDS instead of SDS, no interaction peak appears but an "upturn" in the scattered intensity is observed at small q value. The magnitude of this effect decreases with increasing surfactant concentration, showing clearly that SDS is capable of breaking up the large aggregates created.     

Isothermal titration calorimetry and dynamic light scattering studies of interactions between gemini surfactants of different structure and Pluronic block copolymers

The interactions between triblock copolymers of poly(ethylene oxide) and poly(propylene oxide), P103 and F108, EO(n)PO(m)EO(n), m=56 and n=17 and 132, respectively, and m-s-m type gemini surfactants, m=8, 10, 12, and 18, and s = 3, 6, 12, and 16, have been studied in aqueous solution using isothermal titration calorimetry and dynamic light scattering techniques. The enthalpograms of F108 as a function of surfactant concentration show one broad peak at polymer concentrations C(p) < or = 0.50 wt%, below the cmc of the copolymer at 25 degrees C. It is attributed to interactions between the surfactant and the triblock copolymer monomer. DLS results show hydrodynamic radii (R(h)) initially consistent with copolymer monomers that change to values consistent with gemini surfactant micelles as the surfactant concentration is increased. In P103 solutions at C(p) > or = 0.05 wt%, two peaks appear in the enthalpograms, and they are attributed to the interactions between the gemini surfactant and the micelle or monomer forms of the copolymer. An origin-based nonlinear fitting program was employed to deconvolute the two peaks and to obtain estimates of peak properties. An estimate of the fraction of copolymer in aggregated form was also obtained. The enthalpy change due to interactions between the surfactants and P103 aggregates is very large compared to values obtained for traditional surfactants. This suggests that extensive reorganization of copolymer aggregates and surrounding solvent occurs during the interaction. DLS results for the P103 systems containing C(p) > or = 0.05% show evidence of very large aggregates in solution, likely P103 micelle clusters. The transitions observed in the hydrodynamic radii are consistent with a breakdown of micelle clusters with addition of gemini surfactant, followed by mixed micelle formation and/or deaggregation into monomer P103. This is followed by interactions similar to those typically observed in surfactant-nonionic polymer systems. Mechanisms for the interaction and the observed structural changes are discussed.     

Surfactant/nonionic copolymer interaction: a SLS, DLS, ITC, and NMR investigation

The interactions between an oxyphenylethylene-oxyethylene nonionic diblock copolymer with the anionic surfactant sodium dodecyl sulfate (SDS) have been studied in dilute aqueous solutions by static and dynamic light scattering (SLS and DLS, respectively), isothermal titration calorimetry (ITC), and 13C and self-diffusion nuclear magnetic resonance techniques. The studied copolymer, S20E67, where S denotes the hydrophobic styrene oxide unit and E the hydrophilic oxyethylene unit, forms micelles of 15.6 nm at 25 degrees C, whose core is formed by the styrene oxide chains surrounded by a water swollen polyoxyethylene corona. The S20E67/SDS system has been investigated at a copolymer concentration of 2.5 g dm(-3), for which the copolymer is fully micellized, and with varying surfactant concentration up to approximately 0.15 M. When SDS is added to the solution, two different types of complexes are observed at various surfactant concentrations. From SLS and DLS it can be seen that, at low SDS concentrations, a copolymer-rich surfactant mixed micelle or complex is formed after association of SDS molecules to block copolymer micelles. These interactions give rise to a strong decrease in both light scattering intensity and hydrodynamic radius of the mixed micelles, which has been ascribed to an effective reduction of the complex size, and also an effect arising from the increasing electrostatic repulsion of charged surfactant-copolymer micelles. At higher surfactant concentrations, the copolymer-rich surfactant micelles progressively are destroyed to give surfactant-rich-copolymer micelles, which would be formed by a surfactant micelle bound to one or very few copolymer unimers. ITC data seem to confirm the results of light scattering, showing the dehydration and rehydration processes accompanying the formation and subsequent destruction of the copolymer-rich surfactant mixed micelles. The extent of interaction between the copolymer and the surfactant is seen to involve as much as carbon 3 (C3) of the SDS molecule. Self-diffusion coefficients corroborated light scattering data.     

Micellization,mixed micellization and solubilization: The role of interfacial interactions

The importance of interfacial Interactions in governing micellization, mixed micellization, polymer-micene complexation and solubilization is examined in this review. A common thermodynamic approach is used to treat these different phenomena involving surfactant self-assembly. In all the cases, the free energy of self-assembly can be decomposed into bulk and interfacial components. The interfacial component arises from two competing contributions. One is due to the free energy of formation of the micellar core-solvent interface while the other is due to the steric and electrostatic interactions among the head groups at the micellar surface. The competition between these two contributions is shown here as determining all the fundamental features of self-assembly. Specifically, we discuss in this review the influence of interfacial interactions on the cooperativity of self-assembly, the critical micelle concentration, the size and size distribution of micelles, the transition from spherical to cylindrical micelles, the non-ideal behavior in mixed surfactants, the complexation or non-complexation of micelles with polymers, the solubilization of aliphatic and aromatic hydrocarbons and the selective and synergistic solubilization of hydrocarbon mixtures.     

Binary mixed micelles of chiral sodium undecenyl leucinate and achiral sodium undecenyl sulfate: I. Characterization and application as pseudostationary phases in micellar electrokinetic chromatography

Sodium 10-undecenyl sulfate (SUS), sodium 10-undecenyl leucinate (SUL) and their five different mixed micelles at varied percent mole ratios were prepared. The critical micelle concentration (CMC), C₂₀, γ_CMC, partial specific volume, methylene group selectivity, mobilities and elution window were determined using a variety of analytical techniques. These surfactant systems were then evaluated as novel pseudostationary phases in micellar electrokinetic chromatography (MEKC). As a commonly used pseudostationary phase in MEKC, sodium dodecyl sulfate (SDS) was also evaluated. The CMC values of SUS and SUL were found to be 26 and 16 mM, respectively, whereas the CMC of mixed surfactants was found to be very similar to that of SUL. The C₂₀ values decreased dramatically as the concentration of SUL is increased in the mixed micelle. An increase in SUL content gradually increased the methylene group selectivity making the binary mixed surfactants more hydrophobic. Linear solvation energy relationships (LSERs) and free energy of transfer studies were also applied to predict the selectivity differences between the surfactant systems. The cohesiveness and the hydrogen bond acidic character of the surfactant systems were found to have the most significant influence on selectivity and MEKC retention. The SUS and SDS showed the strongest while SUL showed the weakest hydrogen bond donating capacity. The basicity, interaction with n and π-electrons of the solute and dipolarity/polarizability were the least significant factors in LSER model for the surfactant systems studied. Free energies of transfer of selected functional groups in each surfactant systems were also calculated and found to be in good agreement with the LSER data.     

Electrolyte effect on adsorption and the phase transition from microstructures to nanostructures in ionic/ionic surfactants mixture

The effect of salt concentration on intermicellar interactions and aggregate structures of anionic and cationic-rich mixtures of CTAB (cetyltrimethylammonium bromide) and SDS (sodium dodecyl sulfate) were investigated with conductometry, surface tension, zeta potential, cyclic voltammetry measurements and by determining the surfactant NMR self-diffusion coefficients. The critical aggregate concentration (CAC), surface excess (Γ(max)), and mean molecular surface area (A(min)) were determined from plots of the surface tension (γ) as a function of the log of total surfactant concentration. The electrochemical behavior of cationic-anionic (catanionic) mixed surfactant and self-assembled surfactant monomers at Pt wire electrode were studied by cyclic voltammetry (CV). A variation in the peak current versus the total concentration of surfactant allow us to evaluate the CAC and related parameters from regular solution theory along with the diffusion coefficient of the electroactive species. It was observed that, for both the planar air/aqueous interface and micellar systems, the nonideality decreased as the amount of electrolyte in the aqueous medium was increased. Finally, we investigated the variations of electrostatic, transfer and steric free energy in phase transition between mixed micelle and vesicle in the presence of electrolyte using the presented model by our groups.     

The sphere-rod transition of micelles of dodecyldimethylammonium bromide in aqueous NaBr solutions,and the effects of counterion binding on the micelle size,shape and structure

Micelle size and shape of dodecyldimethylammonium bromide have been determined by measurement of light scattering from its aqueous NaBr solutions. In water and in the presence of NaBr up to 0.07 M, the Debye plots give straight lines with positive slopes, and spherical micelles having molecular weight less than 30 000 are formed. At higher NaBr concentrations, the Debye plots decrease with increasing micelle concentration, indicating the aggregation of the primary spherical micelles into larger secondary micelles. The molecular weight and the radius of gyration of the secondary micelles increase with increasing NaBr concentration, and the relation between molecular weight and radius of gyration suggests that they are rodlike and flexible. Linear logarithmic relations between micelle molecular weight and ionic strength hold for spherical and rodlike micelles, respectively, and the threshold concentration of NaBr for the sphere-rod transition is located at 0.07 M. The spherical micelle of dodecyldimethylammonium ions has a size more than 20 surfactant ions larger in NaBr solutions than in NaCl solutions, and their rodlike micelle has a shorter length in NaBr solutions than in NaCl solutions, when compared at an identical aggregation number, indicating 2 more surfactant ions in its cross-section.     

Free energy profiles for penetration of methane and water molecules into spherical sodium dodecyl sulfate micelles obtained using the thermodynamic integration method combined with molecular dynamics calculations

The free energy profiles, ΔG(r), for penetration of methane and water molecules into sodium dodecyl sulfate (SDS) micelles have been calculated as a function of distance r from the SDS micelle to the methane and water molecules, using the thermodynamic integration method combined with molecular dynamics calculations. The calculations showed that methane is about 6-12 kJ mol(-1) more stable in the SDS micelle than in the water phase, and no ΔG(r) barrier is observed in the vicinity of the sulfate ions of the SDS micelle, implying that methane is easily drawn into the SDS micelle. Based on analysis of the contributions from hydrophobic groups, sulfate ions, sodium ions, and solvent water to ΔG(r), it is clear that methane in the SDS micelle is about 25 kJ mol(-1) more stable than it is in the water phase because of the contribution from the solvent water itself. This can be understood by the hydrophobic effect. In contrast, methane is destabilized by 5-15 kJ mol(-1) by the contribution from the hydrophobic groups of the SDS micelle because of the repulsive interactions between the methane and the crowded hydrophobic groups of the SDS. The large stabilizing effect of the solvent water is higher than the repulsion by the hydrophobic groups, driving methane to become solubilized into the SDS micelle. A good correlation was found between the distribution of cavities and the distribution of methane molecules in the micelle. The methane may move about in the SDS micelle by diffusing between cavities. In contrast, with respect to the water, ΔG(r) has a large positive value of 24-35 kJ mol(-1), so water is not stabilized in the micelle. Analysis showed that the contributions change in complex ways as a function of r and cancel each other out. Reference calculations of the mean forces on a penetrating water molecule into a dodecane droplet clearly showed the same free energy behavior. The common feature is that water is less stable in the hydrophobic core than in the water phase because of the energetic disadvantage of breaking hydrogen bonds formed in the water phase. The difference between the behaviors of the SDS micelles and the dodecane droplets is found just at the interface; this is caused by the strong surface dipole moment formed by sulfate ions and sodium ions in the SDS micelles.     

β-CD对SDS胶束生成与特性的影响

通过胶束的扩散系数D、聚集数N和β-CD在SDS胶束与水连续相间的分配系数P的测定,研究了β-CD对SDS胶束特性的影响.结果表明,β-CD浓度较小时,随着β-CD的加入,其在SDS胶束相中的分配增大,胶束的扩散系数D与聚集数N均降低.β-CD浓度较大时,其在水连续相中的分配增加,对SDS胶束的扩散系数D与聚集数N的影响显著降低.SDS浓度小于第一CMC,β-CD与SDS单体形成1∶1的包合物;SDS浓度大于第一CMC,β-CD与SDS形成1:8的混合球形胶束.