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We present the phase diagram and the microstructure of the binary surfactant mixture of AOT and C(12)E(4) in D(2)O as characterized by surface tension and small angle neutron scattering. The micellar region is considerably extended in composition and concentration compared to that observed for the pure surfactant systems, and two types of aggregates are formed. Spherical micelles are present for AOT-rich composition, whereas cylindrical micelles with a mean length between 80 and 300 ? are present in the nonionic-rich region. The size of the micelles depends on both concentration and molar ratio of the surfactant mixtures. At higher concentration, a swollen lamellar phase is formed, where electrostatic repulsions dominate over the Helfrich interaction in the mixed bilayers. At intermediate concentrations, a mixed micellar/lamellar phase exists. 相似文献
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Tsuneo Okubo 《Colloid and polymer science》2011,289(2):159-167
Drying dissipative patterns were observed at room temperature on a cover glass, a watch glass, and a Petri glass dish during
the course of dryness of aqueous solution of sodium salts of dextran sulfate (NaDSS) having molecular weights of 5000, 36,000 ~ 50,000
and 500,000. These biopolyelectrolytes are one of the typical polysaccharides. The influences of the hexose units upon the
macroscopic and microscopic drying patterns are studied. Formation of some ordered structure is observed for NaDSS in high
polymer concentrations especially on a cover glass. Broad ring size decreased as polymer concentration decreased and/or its
molecular weight increased. Drying patterns are clarified to be formed by the successive and cooperative pattern formation
of convection, sedimentation, and solidification. 相似文献
4.
Tsuneo Okubo Tomio Yamada Keisuke Kimura Akira Tsuchida 《Colloid and polymer science》2006,284(4):396-404
Macroscopic and microscopic dissipative structural patterns formed in the course of drying a series of poly (ethylene glycol)
(PEG) having molecular weights ranging from 1,000 to 2×106 in aqueous solution have been studied on a cover glass. The broad ring patterns of the hill accumulated with the polymers
are formed irrespective of the molecular weights of PEG molecules. The single round hills are formed also in the center in
the macroscopic scale, when the molecular weight is large. The characteristic convection flow of the polymers and the interactions
among the polymers and substrate are important for the macroscopic pattern formation. Cross-like fractal patterns are observed,
especially for the diluted solutions in the microscopic scale. These patterns are determined mainly by the electrostatic and
polar interactions between the polymers and/or between the polymer and the substrate in the course of solidification. Interestingly,
these microscopic patterns are reflected based on the shape and size of the PEG polymers. 相似文献
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Macroscopic and microscopic dissipative structural patterns formed in the course of drying the fractionated and monodisperse bentonite particles (plate-like in their shape) in aqueous deionized suspension and in the presence of NaCl have been studied on a cover glass. The patterns coexisted with the broad ring of the hill accumulated with the particles and with the round hills are formed around the outside edges of the film and in the center, respectively, in the macroscopic scale. By the addition of NaCl the pattern shifts from the broad ring to the round hill in the center. The spoke-like cracks, which have been observed for the suspensions of the spherical particles so often hitherto, are not observed at all for the bentonite suspensions. The characteristic convection flow of the particles and the interactions among the particles and substrate are important for the macroscopic pattern formation. Wrinkled, branch-like and/or star-like fractal patterns are observed in the microscopic scale. These patterns are determined mainly by the electrostatic and polar interactions between the particles and/or between the particle and the substrate in the course of drying. 相似文献
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Macroscopic and microscopic drying patterns of arrowroot starch (ARS) in diluted aqueous solution and gel state were investigated on a cover glass in order to know the molecular information of ARS and their interaction with the substrate. Thickness profiles of the dried film showed coexistence of the rather sharp broad ring and the very broad accumulation at the outside edge and the inner region, respectively. The sharpness parameters, S values from the outside peaks decreased sharply from 100 to 3 as initial concentration increased from 0.04 to 3 wt%. Furthermore, very low S values between one and two originating from the round hills were also observed at low concentrations, 0.04 to 0.2 wt%. The results support that stable gelation of ARS molecules does not take place at the ARS concentrations lower than ca. 2 wt% at 20 °C. It is highly plausible that ARS molecules existing near the substrate surface are adsorbed strongly on the substrate. Gelation of ARS molecules took place rapidly above 2 wt%. The S values increased sharply from 3 to 15 with increasing temperature from 5 to 20 °C, and kept constant around 15 at the higher temperatures up to 50 °C. Convectional diffusion of ARS decreased in the order of ARS > gelatin > poly (N-butyl acrylate), when comparison was made at the same weight percent at the lower concentrations than ca. 2 wt%. Above the concentration, stable gel structures of ARS were formed. 相似文献
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Drying dissipative structures of the aqueous suspensions of palygorskite and tungstic acid particles
Macroscopic and microscopic dissipative structural patterns during dryness of the aqueous suspensions of palygorskite (PGK,
needle-like shaped) and tungstic acid (TA, plate-like) have been studied on a cover glass. The coexistence of the broad ring
of the hill accumulated with the particles and the round hills is observed around the outside edges of the dried film and
in the center, respectively. These patterns differ from those of the suspensions of spherical particles. Furthermore, the
spoke-like patterns, which have been observed for the suspensions of the spherical particles so often, are not observed at
all for PGK and TA suspensions. These characteristic macroscopic patterns of PGK and TA are quite similar to those of the
fractionated and monodispersed bentonites (plate-like) reported previously Yamaguchi et al. (Colloid Polymer Sci 283:1123,
2005). Wrinkled and/or branch-like fractal patterns are observed in the microscopic scale, which are quite similar to those of
bentonites. “Shape information” of the colloidal particles is clarified to be “transferred” to the drying patterns via the
convectional and sedimentary patterns during the course of dryness. 相似文献
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Marek ?váb Martina ?vábová Petra Me?í?ová 《Central European Journal of Chemistry》2011,9(6):1150-1157
This study examined the direct spectrometric method for determining non-ionic surfactants in highly-polluted samples (i.e., soil leachates) containing high concentrations of humic acids. Meso-tetra-(3,5-dibromo-4-hydrooxyphenyl)-porphyrin served
as a coloration agent. The method was tested by use of two polyethoxylate/polypropoxylate — based non-ionic surfactants: Triton
CF-21 containing aromatic groups in the structure and Novanik 1047A containing only linear hydrocarbon chains. The main goal
was to quantify the influence of interfering species to the results. A test for coincidence of regression lines was employed
for objective evaluation of the humic acid influence on the determination. It was observed that for linear surfactant Novanik
1047 A the method provides reliable result and thus, can serve for routine analyses. Regarding Triton CF-21, an interfering
effect of humic acids was observed; however, after sufficient dilution of the samples, the method can be used as well. Finally,
the method can be used for simple analyses of problematic samples without complicated sample-pretreatment.
相似文献
10.
Conformational states of poly(oxyethylene) chain in aqueous solution are examined in connection with hydrophilic property of nonionic surfactants. The Raman spectra in various states are analyzed on the basis of comprehensive normal coordinate treatment. The poly(oxyethylene) chain is more ordered in more dilute aqueous solution. This conformational ordering is further promoted by lowering temperature. The ordered structure, which is similar, at least in part, to that in the solid state, is substantiated by the hydrogen bonds making the gauche conformation of the OCH2-CH2O group more favorable. The hydration has no significant effect on the conformation of the CH2O-CH2CH2 group. 相似文献
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The mechanism of hydroxide ion binding to nonionic surfaces is explored by variation of the properties of the water-aggregate interface and by variation of the type of the aggregate. 相似文献
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Drying dissipative patterns of the linear-type thermosensitive homopolymer poly(N-isopropylacrylamide) lpNIPAm in deionized aqueous solution and suspension were observed on a cover glass, a watch glass, and a Petri glass dish at 22 and 50 °C, respectively. The size and ζ potential of the globule aggregates of lpNIPAm at 47.5 °C were 140 nm in diameter and ?22 mV from the electrophoretic light-scattering measurements. A single broad ring formed in the inner region (on a cover glass and a watch glass) and near the outside edge (in a glass dish) in the macroscopic drying pattern at 22 °C. On the other hand, two to three kinds of broad rings were observed at the outside edge and inner region at 50 °C. Microscopic drying structures of ordered rings, flickering ordered spoke-lines, and net structures of the agglomerated particles were observed. Formation of the similar-sized agglomerates and their ordered arrays were observed during the course of dryness. These results of lpNIPAm at 50 °C are quite similar to the agglomeration and the ordering of the thermosensitive gel spheres of poly(N-isopropylacrylamide), pNIPAm. The surface structures of the similar-sized agglomerates of lpNIPAm will be similar to those of pNIPAm gel spheres, since the chemical components of the homopolymers and the gels are almost the same. The role of the electrical double layers around the agglomerates and their interaction with the substrates are important for the ordering. Dendritic large aggregates (from 50 to 600 μm in size) formed in the presence of sodium chloride. 相似文献
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Using CD-measurements the influence of nonionic surfactants (dodecyl polyoxyethylene, ethoxylated para tert. octyl phenol, commercial nonionic WON 100 and octyl diethyl phosphinoxid) on the secondary structure of gelatin in aqueous solutions was investigated. At surfactant concentrations smaller than the c.m.c. the triple helical content of the gelatin is increased. At concentrations exceeding the c.m.c. the triple helical content decreases. Chain reversals of the peptide chains after the destruction of the triple helical structure were shown to appear in acidic environment at 298 K. This destruction is reversible by rechilling the solution. 相似文献
14.
FitzGerald PA Carr MW Davey TW Serelis AK Such CH Warr GG 《Journal of colloid and interface science》2004,275(2):649-658
Dimeric poly(ethylene oxide) surfactants (or nonionic gemini surfactants) with the structure (Cn-2H2n-3CHCH2O(CH2CH2O)mH)2(CH2)6 (or GemnEm), where n is the alkyl length and m is the average number of ethylene oxides per head group, were synthesized. Surfactants were synthesized with alkyl chain lengths n = 12, 14, and 20 and m = 5, 10, 15, 20, and 30. Water solubilities and cloud temperatures at 1 wt% were determined by measuring turbidity as a function of temperature. Cloud temperatures increase with m and decrease with n, as observed for conventional surfactants. For large m the cloud temperatures were all above 100 degrees C. Surfactants with small m (i.e., n = 12, 14, m = 5 and n = 20, m = 10) were insoluble at room temperature, forming two-phase mixtures. Critical micelle concentrations (CMCs) were measured using a pyrene fluorescence method and are all in the range of 10(-7) to 10(-6) M, with the lowest values from the surfactants with large n and small m. CMCs of mixtures with both anionic and nonionic conventional (monomeric) surfactants were well described by an ideal mixing model. 相似文献
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Syuji Fujii Yuma Yamashita Yoshinobu Nakamura Tsuneo Okubo 《Colloid and polymer science》2014,292(10):2621-2631
Drying dissipative patterns of cationic gel crystals of lightly cross-linked poly(2-vinylpyridine) spheres (CAIBA-P2VP(0.1), CAIBA-P2VP(0.5), and CAIBA-P2VP(1), 107?~?113 nm in diameter and 0.1, 0.5, and 1 in degrees of cross-linking) were observed on a cover glass, a watch glass, and a Petri glass dish. Convectional spoke line and cluster patterns were recognized with the naked eyes, which supports that these poly(2-vinylpyridine) gel spheres aggregate temporarily and reversibly during the course of drying. Two kinds of broad rings were observed at the outside edge and inner region in the macroscopic drying pattern. The size of the inner rings decreased with gel concentration. Formation of similar-sized aggregates (or agglomerates) and their ordered arrays ((a) ordered ring, (b) spoke lines, (c) net structures, and (d) lattice structures) were observed, though the arrays were not so complete compared with those of large-sized analogous gel spheres. One of the main causes of the incomplete ordering of the aggregates is the rather high polydispersities in the sphere size. The ordering of similar-sized aggregates is common among the gel spheres including anionic poly(N-isopropylacrylamide) and cationic poly(2-vinylpyridine). Size effect of cationic gel spheres on the ordering of the agglomerates was clarified definitely in this work. The role of the convectional flow and the electrical double layers around the agglomerates and their interaction with the substrates during drying was also clarified to be very important for the drying pattern formation. 相似文献
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Tsuneo Okubo Junichi Okamoto Shinya Takahashi Akira Tsuchida 《Colloid and polymer science》2009,287(8):933-942
Drying dissipative structures of aqueous solution of poly(ethylene glycol) (PEG) of molecular weights ranging from 200 to
3,500,000 were studied on a cover glass, a watch glass, and a glass dish on macroscopic and microscopic scales. Any convectional
and sedimentation patterns did not appear during the course of drying the PEG solutions. Several important findings on the
drying patterns are reported. Firstly, the crystalline structures of the dried film changed from hedrites to spherulites as
the molecular weight and/or concentration of PEG increased. Secondly, lamellae were formed along the ring patterns especially
at high concentrations and high molecular weights. The coupled crystalline patterns of the spherulites and the lamellae were
observed in a watch glass along the ring structures, supporting the important role of the convection by the gravity during
the course of dryness. The coupled patterns were difficult to be formed on a cover glass and a glass dish, except at the outside
edge of the dried film. Thirdly, the size of the broad ring at the outside edge of the dried film especially on a cover glass
and a watch glass increased sharply as the molecular weight increased and also as the polymer concentration increased.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
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《Journal of membrane science》1998,147(1):13-22
The effects of nonionic surfactants having different hydrophilicity and membranes having different hydrophobicity and molecular weight cut-off on the performance of micellar-enhanced ultrafiltration (MEUF) process were examined. A homologous series of polyethyleneglycol (PEG) alkylether having different numbers of methylene groups and ethylene oxide groups was used for nonionic surfactants. Polysulfone membranes and cellulose acetate membranes having different molecular cut-off were used for hydrophobic membranes and hydrophilic membranes, respectively. The concentration of surfactant added to pure water was fixed at the value of 100 times of critical micelle concentration (CMC). The flux through polysulfone membranes decreased remarkably due to adsorption mainly caused by hydrophobic interactions between surfactant and membrane material. The decline of solution flux for cellulose acetate membranes was not as serious as that for polysulfone membranes because of hydrophilic properties of cellulose acetate membranes. The surfactant rejections for the cellulose acetate membranes increased with decreasing membrane pore size and with increasing the hydrophobicity of surfactant. On the other hand the surfactant rejections for polysulfone membranes showed totally different rejection trends with those for cellulose acetate membranes. The surfactant rejections for the polysulfone membranes depend on the strength of hydrophobic interactions between surfactant and membrane material and molecular weight of surfactants. 相似文献
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Shoichi Ikeda Gerald D. Fasman 《Journal of polymer science. Part A, Polymer chemistry》1970,8(4):991-1001
The absorption and fluorescence spectra of a detergent, polyoxyethylene octylphenyl ether, were measured in water at different concentrations. The absorption spectra had a peak at 275 mμ and a shoulder at 281 mμ. The spectra were independent of concentration below the critical micelle concentration, but the molar extinction coefficients of the peak and the shoulder increased with concentration above the critical micelle concentration. The critical micelle concentration value derived from the absorption data was in good agreement with those obtained by other methods. The fluorescence spectra of the detergent in water were independent of concentration in dilute solutions, if the intensities of the spectra were normalized at the peak at 302 mμ. At higher concentrations, a weak excimer band appeared at 345 mμ, whose intensity increased with concentration. The excimer band manifested itself at a concentration slightly lower than the critical micelle concentration. The main band decreased and the excimer band increased, as the temperature was raised. An excimer band was observed in the same region of the spectra for the pure detergent, either in the solid or liquid state. The equilibrium solid spectra exhibited a very strong excimer emission. It was concluded that the excimers were formed within micelles in the case of aqueous solutions. 相似文献