Phase behavior and microstructures of nonionic fluorocarbon surfactant in aqueous systems

The phase behavior and self-assembled structures of perfluoroalkyl sulfonamide ethoxylate, C8F17SO2N(C3H7)(CH2CH2O)20H (abbreviated as C8F 17EO20), a nonionic fluorocarbon surfactant in an aqueous system, has been investigated by the small-angle X-ray scattering (SAXS) technique. The C8F17EO20 forms micelles and different liquid crystal phases depending on the temperature and composition. The fluorocarbon micellar structure induced by temperature or composition change and added fluorocarbon cosurfactant has been systematically studied. The SAXS data were analyzed by the indirect Fourier transformation (IFT) and the generalized indirect Fourier transformation (GIFT) depending on the volume fraction of the surfactant and complemented by plausible model calculations. The C8F17EO20 forms spherical type micelles above critical micelle concentration (cmc) in the dilute region. The micelle tends to grow with temperature; however, the growth is not significant on changing temperature from 15-75 degrees C, which is attributed to the higher clouding temperature of the surfactant (>100 degrees C). On the other hand, the micellar structure (shape and size) is apparently unaffected by composition (1-25 wt %) at 25 degrees C. Nevertheless, addition of fluorocarbon cosurfactant of structure C8F17SO2N(C3H7)(CH2CH2O)H (abbreviated as C8F17EO1) to the semidilute solution of C8F17EO20 (25 wt %) favors micellar growth, which finally leads to the formation of viscoelastic wormlike micelles, as confirmed by rheometry and supported by SAXS. The onset sphere-to-wormlike transition in the structure of micelles in the C8F17EO20/water/C8F17EO1 system is due to the fact that the C8F17EO1 tends to go to the surfactant palisade layer so that the critical packing parameter increases due to a decrease in the effective cross-sectional area of the headgroup. As a result, spherical micelles grow into a cylinder, which after a certain concentration entangle to form a rigid network structure of wormlike micelles.     

Thermodynamic‐Dependent Size‐Selection of ZnSe Nanoparticles in Amphiphilic Triblock Copolymer Systems

ZnSe colloidal nanoparticles prepared by the air‐insensitive starting reagents, zinc chloride and selenium powder, have been size‐selected in the Pluronic amphiphilic triblock copolymer [(EO)_x(PO)_y(EO)_x] systems. The size‐selection mechanism between the ZnSe nanoparticles and the triblock copolymers systems is a thermodynamic‐dependent effect. We observe that nanoparticles with special volume (Vs) are trapped first by the triblock copolymers due to the faster entropic depletion interaction arising from the addition of surfactant‐template (micelles) to colloidal nanoparticles. On the other hand, nanoparticles with sizes larger or smaller than Vs will not interact with the surfactant‐templates. They either precipitate quickly by gravity (larger than Vs) or still retain their thermal motion in the aqueous phase (smaller than Vs) when Vs nanoparticles are caught by the surfactant‐templates.     

Preparation of stable electroneutral nanoparticles of sodium dodecyl sulfate and branched poly(ethylenimine) in the presence of pluronic F108 copolymer

Mixing of polyelectrolyte solutions with solutions of oppositely charged surfactants usually leads to phase separation in a certain concentration range. However, since the charge-neutralized polyelectrolyte/surfactant nanoparticles might be utilized as versatile nanocarriers of different substances, it would be desirable to prevent their aggregation for some applications. As it was revealed in earlier investigations, the complete suppression of precipitation may be achieved only in mixtures of ionic surfactants and appropriate copolymer polyelectrolytes with nonionic and ionic blocks. In this work, we present a method that could prevent phase separation in mixtures of homopolyelectrolytes and oppositely charged surfactants. Specifically, it is shown that nonaggregating electroneutral nanocomplexes of branched poly(ethylenimine) (PEI) and sodium dodecyl sulfate (SDS) can be prepared in the presence of the amphiphilic triblock copolymer Pluronic F108, provided that an adequate mixing protocol is used for preparation of the PEI/SDS/F108 mixtures.     

Micellar ordered structure effects on high‐resolution CE‐SSCP using Pluronic triblock copolymer blends

Pluronic F108 block copolymers have shown a great promise to achieve the desirable high resolution in the conformation‐sensitive separation of ssDNA using CE‐SSCP. However, fundamental understanding of the structures and properties of Pluronic matrix affecting the resolution is still limited. Unlike conventional gel‐forming homopolymers, Pluronic F108 block copolymers are amphiphilic macromolecules consisting of poly(ethylene oxide)‐b‐poly(propylene oxide)‐b‐poly(ethylene oxide) triblock copolymers, which are capable of forming a highly ordered micellar structure in aqueous solution. In this study, we have performed a series of experiments by blending different types of Pluronic polymers to control the formation of micelles and to study the correlation between separation and rheological characteristics of Pluronic gels affecting the resolution of CE‐SSCP. Our experiments have been specifically designed to elucidate how the micellar structure affects the resolution of CE‐SSCP upon altering the size uniformity and constituent homogeneity of the micelles. Our results suggest that uniformly sized micelle packing is the primary structural feature of Pluronic gel matrix for the high‐resolution separation, while the size and constituent of the micelle themselves need to be considered as secondary factors.     

Time-resolved in situ studies of the formation of cubic mesoporous silica formed with triblock copolymers

The mechanism of formation of two different cubic mesoporous silica materials formed with Pluronic triblock copolymers is investigated with in situ time-resolved small-angle synchrotron X-ray scattering, in situ time-resolved 1H nuclear magnetic resonance, and time-resolved transmission electron microscopy. The materials studied are the micellar cubic (Imm) SBA-16 formed with Pluronic F108 and the bicontinuous cubic (Iad) silica material formed with Pluronic P103 and NaI. The formation mechanisms of the two cubic structures are shown to be dissimilar. For the Imm material, in the early stages of the synthesis, flocs of unordered micelles are observed, but areas where the micelles have started to order are also present. With time, there is an increase in order; however, there is a coexistence of unordered micelles and ordered material all through this study. The bicontinuous cubic silica is formed via a different path. The system is phase-separated already before the addition of the silica source, which implies that a concentrated phase is present, acting as the structure director of the Iad structure. The results are compared with earlier reports on the formation of the hexagonal SBA-15 material.     

Small-angle X-ray scattering (SAXS) study on nonionic fluorinated micelles in aqueous system

We have investigated the self-organization structures of perfluoroalkyl sulfonamide ethoxylate, C(8)F(17)SO(2)N(C(3)H(7))(CH(2)CH(2)O)(10)H, a nonionic fluorinated surfactant in aqueous system by small-angle X-ray scattering (SAXS) technique. Structural modulation of the nonionic fluorinated micelle induced by temperature change, surfactant concentration, and the added fluorinated oils have been systematically studied. The SAXS data were analyzed by the indirect Fourier transformation (IFT), and the generalized indirect Fourier transformation (GIFT) depending on the volume fraction of the surfactant. Various plausible classical model calculations have been performed to confirm the consistency of the GIFT analysis of the SAXS data. Upon successive increase in temperature, the cylindrical micelles formed at lower temperatures undergo a continuous one-dimensional growth and ultimately near the cloud point an indication of flat planar like structural pattern is observed. The evolution in structure of particle near the demixing temperature may be due to onset of attractive interactions. The shape and size of the micelle is apparently unaffected by changing the surfactant concentration from 1 to 5 wt% at 25 degrees C. Nevertheless, addition of small amount of perfluoropolyether (PFPE) oil, of structure F(CF(2)CF(2)CF(2)O)(n)CF(2)CF(2)COOH (n approximately 21) modulate the micellar shape and size. Long cylindrical micelles eventually transform into globular like particles. The onset cylinder-to-sphere transition in the structure of micelles in the surfactant/water/oil system is probably due to amphiphilic nature of the oil, which tends to increase the spontaneous curvature. The lipophilic part of the oil tends to reside in the micellar core, whereas, the hydrophilic part goes close to the polar head group of the surfactant so that effective cross-sectional area per surfactant molecules increases and as a result spherical micelles tend to form. Perfluorodecalin (PFD) also decreases size of the micelles but its effect is poor compared to the PFPE oil.     

Shifts in polystyrene particle surface charge upon adsorption of the Pluronic F108 surfactant

Electrical field-flow fractionation (ElFFF) and sedimentation field-flow fractionation (SdFFF) were used in combination to study the adsorption of the triblock polymeric surfactant, Pluronic F108 [(EO)129-(PO)56-(EO)129] to 200 nm polystyrene (PS) latex spheres. The SdFFF technique allowed an accurate determination of the mass of surfactant adsorbed on each particle from a solution of given concentration. To complement this isotherm study, we show that ElFFF can be used to measure fractional coverages of the formed electrically neutral surfactant layers on the charged PS particles. Through a combination of the two techniques it is possible to gain information about the structure of the adsorbate layer. Thus, when Pluronic F108 is taken up by the PS surface from solutions of low concentration, all three blocks appear to adhere to the surface as long as there is free space available. As the solution concentration increases and the fractional coverage reaches approximately 20%, the surface turns crowded enough to let the strongly adsorbing PPO blocks competitively displace the weakly adherent PEO blocks, which gradually rise to extend into the aqueous phase until the surface is fully saturated.     

Metalated diblock and triblock poly(ethylene oxide)-block-poly(4-vinylpyridine) copolymers: understanding of micelle and bulk structure

The paper provides new insights into the structure of Pt-containing diblock and triblock copolymers based on poly(ethylene oxide) (PEO) and poly(4-vinylpyridine) (P4VP), using a combination of atomic force microscopy (AFM), X-ray diffraction (XRD), transmission electron microscopy (TEM), and anomalous small-angle X-ray scattering (ASAXS). Parallel studies using methods contributing supplemental structural information allowed us to comprehensively characterize sophisticated polymer systems during metalation and to exclude possible ambiguity of the data interpretation of each of the methods. AFM and TEM make available the determination of sizes of the micelles and of the Pt-containing micelle cores, respectively, while a combination of XRD, TEM, and ASAXS reveals Pt-nanoparticle size distributions and locations along with the structural information about the polymer matrix. In addition, for the first time, ASAXS revealed the organization of Pt-nanoparticle-filled diblock and triblock copolymers in the bulk. The nanoparticle characteristics are mainly determined by the type of block copolymer system in which they are found: larger particles (2.0-3.0 nm) are formed in triblock copolymer micelles, while smaller ones (1.5-2.5 nm) are found in diblock copolymer micelles. This can be explained by facilitated intermicellar exchange in triblock copolymer systems. For both systems, Pt nanoparticles have narrow particle size distributions as a result of a strong interaction between the nanoparticle surface and the P4VP units inside the micelle cores. The pH of the medium mainly influences the particle location rather than the particle size. A structural model of Pt-nanoparticle clustering in the diblock PEO-b-P4VP and triblock P4VP-b-PEO-b-P4VP copolymers in the bulk was constructed ab initio from the ASAXS data. This model reveals that nearly spherical micellar cores of about 10 nm in diameter (filled with Pt nanoparticles) aggregate forming slightly oblate hollow bodies with an outer diameter of about 40 nm.     

Tuning of the Temperature Window for Unit‐Cell and Pore‐Size Enlargement in Face‐Centered‐Cubic Large‐Mesopore Silicas Templated by Swollen Block Copolymer Micelles

The unit‐cell size and pore diameter as functions of temperature are investigated in the syntheses of FDU‐12 silicas with face‐centered cubic structure templated by Pluronic (PEO‐PPO‐PEO) block copolymer micelles swollen by toluene. The temperature range in which the unit‐cell size and pore size strongly increase as temperature decreases is correlated with the critical micelle temperature (CMT) of the surfactant. While Pluronic F127 affords a wide range of unit‐cell parameters (28–51 nm) and pore diameters (16–32 nm), it renders moderately enlarged pore sizes at 25 °C. The use of Pluronic F108 with higher CMT affords FDU‐12 with very large unit‐cell size (～49 nm) and large pore diameter (27 nm) at 23 °C. Large unit‐cell size (40–41 nm) and pore size (22 nm) were obtained even at 25 °C. The application of Pluronics F87 and F88 with much smaller molecular weights and higher CMTs also allows one to synthesize FDU‐12 with quite large unit‐cell parameters and pore sizes at room temperature. The present work demonstrates that one can judiciously select Pluronic surfactants with appropriate CMT to shift the temperature range in which the pore diameter is readily tunable.     

Effect of added poly(oxyethylene)dodecyl ether on the phase and rheological behavior of wormlike micelles in aqueous SDS solutions

Upon the addition of a short EO chain nonionic surfactant, poly(oxyethylene) dodecyl ether (C12EOn), to dilute micellar solution of sodium dodecyl sulfate (SDS) above a particular concentration, a sharp increase in viscosity occurs and a highly viscoelastic micellar solution is formed. The oscillatory-shear rheological behavior of the viscoselastic solutions can be described by the Maxwell model at low shear frequency and combined Maxwell-Rouse model at high shear frequency. This property is typical of wormlike micelles entangled to form a transient network. It is found that when C12EO4 in the mixed system is replaced by C12EO3 the micellar growth occurs more effectively. However, with the further decrease in EO chain length, phase separation occurs before a viscoelastic solution is formed. As a result, the maximum zero-shear viscosity is observed at an appropriate mixing fraction of surfactant in the SDS-C12EO3 system. We also investigated the micellar growth in the mixed surfactant systems by means of small-angle X-ray scattering (SAXS). It was found from the SAXS data that the one-dimensional growth of micelles was obtained in all the SDS-C12EOn (n=0-4) aqueous solutions. In a short EO chain C12EOn system, the micelles grow faster at a low mixing fraction of nonionic surfactant.     

Formation of gold@polymer core-shell particles and gold particle clusters on a template of thermoresponsive and pH-responsive coordination triblock copolymer

Template synthesis of various morphological gold colloidal nanoparticles using a thermoresponsive and pH-responsive coordination triblock copolymer of poly(ethylene glycol)-b-poly(4-vinylpyridine)-b-poly(N-isopropylacrylamide) is studied. The template morphology of the thermoresponsive and pH-responsive coordination triblock copolymer, which can be tuned by simply changing the pH or temperature of the triblock copolymer aqueous solution, ranges from single chains to core-corona micelles and further to micellar clusters. Various morphological gold colloidal nanoparticles such as discrete gold nanoparticles, gold@polymer core-shell nanoparticles, and gold nanoparticle clusters are synthesized on the corresponding template of the triblock copolymer by first coordination with gold ions and then reduction by NaBH4. All three resultant gold colloidal nanoparticles are stable in aqueous solution, and their sizes are 2, 10, and 7 nm, respectively. The gold@polymer core-shell nanoparticles are thermoresponsive. The gold nanoparticle cluster has a novel structure, and each one holds about 40 single gold nanoparticles.     

Viscoelastic micellar solutions in nonionic fluorinated surfactant systems

The formation and rheological behavior of a viscoelastic wormlike micellar solution in an aqueous solution of a nonionic fluorinated surfactant, perfluoroalkyl sulfonamide ethoxylate, of structure C8F17SO2N(C3H7)(CH2CH2O)10H was studied. Temperature-induced viscosity growth is observed even at low-surfactant concentration (approximately 1 wt %), and viscosity reaches the maximum at a temperature T(eta)-max. Upon successive increases in the temperature, the viscosity decreases, and ultimately a phase separation occurs. Small-angle X-ray scattering (SAXS) measurements confirm the presence of cylindrical aggregates at low temperature, which undergo continuous one-dimensional growth with increasing temperature, and ultimately, an indication of a slight lamellarlike structural pattern is observed, which probably comes from the formation of micellar joints or branching. Such changes in the microstructure result in a decrease in the viscosity and stress-relaxation time, while the network structure is retained; the trends in the evolution of shear modulus (Go) and relaxation time (tauR) with temperature are in agreement with this. With increased surfactant concentration, the temperature corresponding to the viscosity maximum (T eta-max) in the temperature-viscosity curve shifts to lower values, and the viscosity at temperatures below or around T eta-max increases sharply. A viscoelastic solution with Maxwellian-type dynamic rheological behavior at low-shear frequency is formed, which is typical of entangled wormlike micelles. Rheological parameters, eta(o) and Go, show scaling relationships with the surfactant concentrations with exponents slightly greater than the values predicted by the living-polymer model, but the exponent of tauR is in agreement with the theory. Dynamic light-scattering measurements indicate the presence of fast relaxation modes, associated with micelles, and medium and slow modes, associated with transient networks. The disappearance of the slow mode and the predominance of the medium mode as the temperature increases support the conclusions derived from SAXS and rheometry.     

Physicochemical investigation of cobalt–iron cyanide nanoparticles synthesized by a novel solid–solid reaction in confined space

Cobalt–iron cyanide (Co_x[Fe(CN)₆]) nanoparticles have been synthesized by a novel solid–solid reaction in the confined space of dry sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reversed micelles dispersed in n-heptane. The reaction has been carried out by mixing two dry AOT/n-heptane solutions containing CoCl₂ and K₄Fe(CN)₆ or K₃Fe(CN)₆ nanoparticles in the micellar core, respectively. By UV-Vis spectroscopy it was ascertained that, after the mixing process, the formation of stable nanoparticles is fast and complete. Microcalorimetric measurements of the thermal effect due to the Co_x[Fe(CN)₆] nanoparticle formation allowed the determination of the stoichiometric ratio (x) and of the molar enthalpy of reaction in the core of AOT reversed micelles. The observed behavior suggests the occurrence of confinement effects and surfactant adsorption on the nanoparticle surface. Further structural information was achieved by small-angle X-ray scattering (SAXS) measurements. From all liquid samples, interesting salt/AOT composites were prepared by simple evaporation of the apolar solvent. Size, crystal structure, and electronic properties of Co_x[Fe(CN)₆] nanoparticles containing composites were obtained by wide-angle X-ray scattering (WAXS) and X-ray photoelectron spectroscopy (XPS).     

Phase behavior and local dynamics of concentrated triblock copolymer micelles

We report a neutron-scattering study to characterize the ordering and local dynamics of spherical micelles formed by the triblock copolymer polyethylene oxide (PEO)--polypropylene oxide (PPO)--polyethylene oxide (Pluronic) in aqueous solution. The study focuses on two Pluronic species, F68 and F108, that have the same weight fraction of PEO but that differ in chain length by approximately a factor of 2. At sufficiently high concentration, both species undergo a sequence of phase changes with increasing temperature from dissolved chains to micelles with liquid-like order to a cubic crystal phase and finally back to a micelle liquid phase. A comparison of the phase diagrams constructed from small-angle neutron scattering indicates that crystallization is suppressed for shorter chain micelles due to fluctuation effects. The intermediate scattering function I(Q,t)I(Q,0) determined by neutron spin echo displays a line shape with two distinct relaxations. Comparisons between I(Q,t)I(Q,0) for fully hydrogenated F68 chains in D2O and for F68 with deuterated PEO blocks reveal that the slower relaxation corresponds to Rouse modes of the PPO segments in the concentrated micelle cores. The faster relaxation is identified with longitudinal diffusive modes in the PEO corona characteristic of a polymer brush.     

Water-induced micellar structures of block copoly(oxyethylene-oxypropylene-oxyethylene) in o-xylene

We previously reported the water-induced micelle formation of copoly(oxyethylene-oxy-propylene-oxyethylene), Pluronic L64, in o-xylene. The micellar properties could be controlled by varying the water to EO ratio (Z) in micelles. in micelles. In this paper, laser light scattering, transient electric birefringence (TEB), and synchrotron small-angle x-ray scattering (SAXS) were used to study the micellar structure at different Z values. Both TEB and SAXS results further confirmed the micellar shape transition from that of a sphere to a nonspherical shape. A comparison between TEB and dynamic light-scattering results as well as the SAXS experiments showed an ellipsoidal shape for micelles when Z > 1.3 with the oblate being the more reasonable form for fitting all the experimental parameters. The degree of asymmetry appeared to be not high. © 1993 John Wiley & Sons, Inc.     

Size-dependent interaction of silica nanoparticles with different surfactants in aqueous solution

The size-dependent interaction of anionic silica nanoparticles with ionic (anionic and cationic) and nonionic surfactants has been studied using small-angle neutron scattering (SANS). The surfactants used are anionic sodium dodecyl sulfate (SDS), cationic dodecyltrimethyl ammonium bromide (DTAB), and nonionic decaoxyethylene n-dodecylether (C(12)E(10)). The measurements have been carried out for three different sizes of silica nanoparticles (8, 16, and 26 nm) at fixed concentrations (1 wt % each) of nanoparticles and surfactants. It is found that irrespective of the size of the nanoparticles there is no significant interaction evolved between like-charged nanoparticles and the SDS micelles leading to any structural changes. However, the strong attraction of oppositely charged DTAB micelles with silica nanoparticles results in the aggregation of nanoparticles. The number of micelles mediating the nanoparticle aggregation increases with the size of the nanoparticle. The aggregates are characterized by fractal structure where the fractal dimension is found to be constant (D ≈ 2.3) independent of the size of the nanoparticles and consistent with diffusion-limited-aggregation-type fractal morphology in these systems. In the case of nonionic surfactant C(12)E(10), micelles interact with the individual silica nanoparticles. The number of adsorbed micelles per nanoparticle increases drastically whereas the percentage of adsorbed micelles on nanoparticles decreases with the increase in the size of the nanoparticles.     

Synthesis of mesoporous silicas in alkaline and acidic media using the systems cetyltrimethylammonium tosylate (CTAT)-Pluronic F127 triblock copolymer and CTAT-Pluronic F68 triblock copolymer as templates

Mesoporous silica materials were synthesized in alkaline and acidic media, using cetyltrimethylammonium tosylate (CTAT), Pluronic triblock copolymers F127 and F68, and mixtures of CTAT with each copolymer in order to investigate the effects of pH, surfactant concentration, and CTAT/triblock copolymer molar ratios on the morphology and texture of the synthesized materials. The results show that the kind of mesoporous materials and their pore size can be tuned by changing not only the pH but also the proportion of components and the nature of the copolymer. In alkaline synthesis, microscopic bicontinuous materials are obtained, which are composed by nanoscopic plate-like particles having slit-shaped pores. In acidic synthesis, on the contrary, monolithic silicas are obtained. These materials are also composed by nanoscopic plate-like particles having slit-shaped pores, although in some cases, the microscopic structures are formed by fused spherical particles. The inclusion of the triblock copolymer in the template composition causes a transformation from a bimodal to a monomodal pore size distribution, leading to small and nearly round pores which are probably formed by copolymer or copolymer-CTAT mixed micelles. The differences between the systems synthesized by CTAT-Pluronic F127 and CTAT-Pluronic F68 are explained on the basis of the different interactions between each copolymer and CTAT.     

Synergistic effects of polymers and surfactants on depletion forces

This work investigates the synergistic effects of a neutral polymer and an anionic surfactant on depletion forces as a function of bulk polymer and bulk surfactant concentration. In this work, we measure the force between a silica particle and a silica plate in aqueous solutions of the polymer and the surfactant using atomic force microscopy. The polymer is the triblock copolymer poly(ethylene oxide-block-propylene oxide-block-ethylene oxide) (Pluronic F108), and the surfactant is sodium dodecyl sulfate (SDS). In F108-only solutions, the force between the silica particle and the silica plate is primarily repulsive for polymer concentrations ranging from 200 to 10 000 ppm. In SDS-only solutions, the net force between the silica surfaces is repulsive at all separations for concentrations below 16 mM SDS and is attractive with a structural force character above 16 mM SDS. When both F108 and SDS are present in the solution, a net attractive force is observed at SDS concentrations as low as 4 mM, a factor of 2 below the critical micelle concentration (cmc). We attribute this synergistic effect to the complexation of F108 with SDS in bulk solution at a critical aggregation concentration (cac) that is less than the cmc, producing a relatively large, charged complex that creates a significant depletion force between the particle and plate.     

温度对萘在Pluronic胶束水溶液中增溶的影响

研究结果表明 ,温度升高促使Pluronic分子形成更加疏水并且具有较大内核的胶束 ,使萘和胶束内核的亲和力增强 ,从而促进萘的增溶。在所考察的F1 0 8和P94二种Pluronic胶束体系中 ,温度对增溶的促进作用 ,前者比后者更为明显。     

Short haired wormlike micelles in mixed nonionic fluorocarbon surfactants

We have studied the rheological behavior of viscoelastic wormlike micellar solution in a mixed system of nonionic fluorinated surfactants, perfluoroalkyl sulfonamide ethoxylate, C(8)F(17)SO(2)N(C(3)H(7))(CH(2)CH(2)O)(n)H abbreviated as C(8)F(17)EO(n) (n=10 and 20). Above critical micelle concentration, the surfactant, C(8)F(17)EO(20) forms small spherical micelles in water and the viscosity of the solution remains constant regardless of the shear rate, i.e., the solutions exhibit Newtonian behavior. However, upon successive addition of the C(8)F(17)EO(10) the viscosity of the solution increases and at certain C(8)F(17)EO(10) concentration, shear-thinning behavior is observed indicating the formation wormlike micelles. Contrary to what is expected, there is a viscosity increase with the addition of the hydrophilic C(8)F(17)EO(20) to C(8)F(17)EO(10) aqueous solutions at certain temperature and concentration, which could be attributed to an increase in rigidity of the surfactant layer and to the shifting of micellar branching to higher temperatures. The oscillatory-shear rheological behavior of the viscoelastic solution can be described by Maxwell model at low frequency. Small-angle X-ray scattering (SAXS) measurements confirmed the formation of small spherical micellar aggregates in the dilute aqueous C(8)F(17)EO(20) solution. The SAXS data shows the one-dimensional growth on the micellar size with increase in the C(8)F(17)EO(10) concentration. Thus, the present SAXS data supports the rheological data.