共查询到20条相似文献,搜索用时 187 毫秒
1.
N. Hattori H. Hirata H. Okabayashi M. Furusaka C. J. O'Connor R. Zana 《Colloid and polymer science》1999,277(1):95-100
The microstructure of the normal micelles formed by dimeric surfactants with long spacers, [Br−(CH3)2N+(C
m
H2
m
+1)-(CH2)
S
-(C
m
H2
m
+1)N+(CH3)2Br−, m = 10 and s = 8, 10 and 12], has been investigated by small-angle neutron scattering and compared with previously reported results for
micelles of the same dimeric surfactants with shorter spacers (m = 10 and s = 2, 3, 4 and 6). It was found that for dimeric surfactants with long spacers (s = 8 and 10), both micellar growth and variation in shape occur to only a small extent, if at all, compared with dimeric surfactants
with short spacers. However, for the dimeric surfactant with the longest spacer, s = 12, the extent of micellar growth and shape variation is also large. These results are due to the differences in conformation
of dimeric surfactants with short spacers (s = 2–6) compared with that of the surfactants with long spacers (s = 8–12).
Received: 15 June 1998 Accepted: 22 July 1998 相似文献
2.
Raman scattering spectra and molecular conformations of bis(quaternaryammonium bromide)-water systems 总被引:1,自引:0,他引:1
The dimeric bis(quaternaryammonium bromide) surfactants, [Br−(CH3)2N+(C
m
H2
m
+1)—(CH2)
s
—(C
m
H2
m
+1)N+(CH3)2Br−, s = 2, 3 and m = 4, 6, 10 and 12, s = 6 and m = 8, 10, 12], have been synthesized and the phase maps of the sm6-8-water, sm6-10-water and sm6-12-water binary systems have
been determined (sm6-8 implies s = 6, m = 8). In order to examine the molecular structures of these solid samples and of their dimeric surfactant-water binary systems,
Raman spectra of the simple dimeric surfactants, sm2-4 and sm3-4, in which crystal structures of the trans- and cis-type conformations
have been determined by single-crystal X-ray diffraction analysis, have been investigated, and Raman bands characteristic
of these skeletal structures were found in the skeletal deformation region. On the basis of these characteristic Raman bands
for the two conformations, it has been concluded that the dimeric surfactants, sm6-8, sm6-10 and sm6-12 also take up a cis-type
conformation in the crystalline state. Furthermore, it has been found that the Raman bands in the C—H stretching, skeletal
stretching and CH2 scissoring regions are sensitive to phase structure.
Received: 21 July 1998 Accepted in revised form: 9 November 1998 相似文献
3.
Badawi AM Fahmy AA Mohamed KA Noor El-Din MR Riad MG 《Applied biochemistry and biotechnology》2012,166(1):22-35
In this paper, four nonionic surfactants with different hydrophilic–lipophilic balance (HLB) based on sorbitan monolaurate
were synthesized by introducing ethylene oxide gas (n = 20, 40, 60, and 80 ethylene oxide units). The chemical structure of the prepared ethoxylated surfactants was confirmed
using Fourier transform-infrared and 1H NMR spectroscopes. The surface tension and thermodynamic properties of the prepared surfactants have been studied. The simultaneous
saccharification and fermentation (SSF) process for ethanol production from microwave/alkali pretreated wheat straw has been
assayed using nonionic surfactants have different ethylene oxide units. Ethanol yield was 82% and 61% for Kluyveromyces marxianus and Saccharomyces cerevisiae, respectively, with the addition of 2.5 g/l of the prepared nonionic surfactant (HLB = 18.2). Results show that the production
of ethanol from microwave/alkali pretreated wheat straw increased with increasing the (HLB) value of the nonionic surfactant. 相似文献
4.
Self-assembled monolayer gold electrode for surfactant analysis 总被引:2,自引:0,他引:2
Marc Gerlache Zühre Senturk Guy Quarin Jean-Michel Kauffmann 《Journal of Solid State Electrochemistry》1997,1(2):155-160
A gold electrode coated with a self-assembled monolayer of octane-thiol (SAM/Au) has been used as an amperometric detector
for the determination of surfactants. This detector operated in the presence of a high percentage of organic solvent and was
adapted to an HPLC System. At the SAM/Au, the electrochemical response of an electroactive tracer (potassium ferricyanide)
was completely inhibited, but, in the presence of a cationic surfactant, the electrochemical reduction was progressively restored.
In flow injection analysis, using the SAM/Au in an amperometric flow-through detector polarised at 0.0 V vs Ag/AgCl, a linear
response (i=f{[surfactant]}) was observed for cationic surfactants e.g. cetylpyridinium chloride in the concentration range 2 × 10−6–1 × 10−3 M. The electrochemical data along with the determination of the ion pair stoichiometry between the redox tracer and the surfactant
suggest an electrochemical response related to ion pair formation and governed by electron transfer by tunneling effect.
Received: 28 January 1997 / Accepted: 7 March 1997 相似文献
5.
Eloi Feitosa Fernanda Rosa Alves Elisabete M. S. Castanheira M. Elisabete C. D. Real Oliveira 《Colloid and polymer science》2009,287(5):591-599
In the millimolar concentration domain (typically 1 mM), dioctadecyldimethylammonium bromide and chloride (DODAX, X representing
Br− or Cl− counterions) molecules assemble in water as large unilamellar vesicles. Differential-scanning calorimetry (DSC) is a suitable
technique to obtain the melting temperature (T
m) characteristic of surfactant bilayers, while fluorescence spectroscopy detects formation of surfactant aggregates, like
bilayers. These two techniques were combined to investigate the assembly of DODAX molecules at micromolar concentrations,
from 10 to 100 μM. At 1 mM surfactant, T
m ≈ 45 °C and 49 °C, respectively, for DODAB and DODAC. DSC and fluorescence of Nile Red were used to show the formation of
DODAX aggregates, at the surfactant concentration as low as 10 μM, whose T
m decreases monotonically with increasing DODAX concentration to attain the value for the ordinary vesicles. The data indicate
that these aggregates are organized as bilayer-like structures. 相似文献
6.
Kallol K. Ghosh Sancheeta Kolay Sunita Bal Manmohan L. Satnami Pierluigi Quagliotto P. R. Dafonte 《Colloid and polymer science》2008,286(3):293-303
The kinetics of the hydrolysis of p-nitrophenyl acetate (PNPA) and p-nitrophenyl diphenyl phosphate (PNPDPP) by hydroxamate ions mediated by gemini surfactants with quaternary ammonium bromide
(16-n-16,2Br−, n = 3, 4, 6, 12) and pyridinium chloride (12py-n-py12,2Cl−, n = 3, 4) head group have been investigated at 27 °C. The gemini surfactant with the pyridinium head group, 12-py-4-py12,2Cl− (tetramethylene-1,4 bis dodecylpyridinium chloride) shows a large rate acceleration effect than that with an ammonium head group, 16-12-16,2Br−, relative to those in water. The apparent pK
a of the hydroxamic acids have been determined in the presence of gemini surfactants. Catalytic system N-phenylbenzohydroxamate/12py-4-py12,2Cl− demonstrated over ~1,590-fold and ~255-fold rate enhancement in the hydrolysis of PNPA and PNPDPP, respectively, for the
identical reaction performed in buffer aqueous media at 27 °C. The second order rate constant and binding constants for reactions
were determined employing pseudophase model for micellar catalysis. 相似文献
7.
Silicone surfactants containing different pendant hydrophilic groups such as diethanol tertiary amine (SHE, nonionic), diethanol
methyl quaternary amine (cationic) and triethyl quaternary amine (cationic) have been synthesized and characterized by 1H and 13C NMR and gel permeation chromatography. The solution behavior of these novel surfactants has also been investigated by surface
tension measurement and a fluorescence method. It has been observed that the surface tension of these surfactants decreases
as a function of time at a very low polymer concentration (1 × 10−4 wt%). At higher concentration (0.1 wt%), the equilibrium surface tensions reached very low values compared to that of typical
polymer surfactants, for example, poly(ethylene oxide–propylene oxide) block copolymer (EPE0.8). In addition, the low I
1/I
3 values of these silicone surfactants indicate the formation of polymer aggregates in aqueous solution, and an extremely low
I
1/I
3 value of SHE (1.06) compared to other polymeric surfactants (EPE0.8) and conventional surfactants [poly(ethylene glycol n-nonyl phenyl ethers), cetyltrimethylammonium bromide, and sodium dodecyl sulfate] indicates its stronger hydrophobicity.
Received: 15 May 2000 Accepted: 18 October 2000 相似文献
8.
Binding of a cationic surfactant ion, dodecylpyridinium ion, to poly(acrylic acids) of low charge densities was examined
by potentiometry using surfactant-selective electrodes in the solutions, where the pH was kept constant by employing a pH
buffering system. The binding of the surfactant counterions was thus able to be studied at a constant pH during the binding
process. The binding took place in two steps, the first cooperative binding step and the second gradual binding step. The
critical association concentration decreased as the pH increased, indicating the predominant role of the electric interaction
in the binding. The binding isotherms obtained at different but constant pH values were analyzed by the matrix method, taking
into account the nearest-neighbor interactions among three different kinds of sites on the polymer: ionized, protonated, and
surfactant-bound. The theoretical analysis could describe only the first step but could not explain the second step. A relatively
large cooperativity parameter, u, was found for the first step and it can be between 3 × 103 and 1 × 104. When the ionic strength was decreased tenfold, the cooperativity of the binding decreased (u∼1 × 103). The binding constants of the isolated site were 5.5–6.0 × 104 kg mol−1 and slightly increased to 6.5 × 104 kg mol−1 as the ionic strength decreased. The deviation of the second step from the theoretical analysis was supposed to arise from
a change of proton dissociation constant in the nonpolar space formed by the bound surfactants.
Received: 29 November 2000/Accepted: 24 January 2001 相似文献
9.
The surfactant effect on the lower critical solution temperature (LCST) of thermosensitive poly(organophosphazenes) with
methoxy-poly(ethylene glycol) and amino acid esters as side groups was examined in terms of molecular interactions between
the polyphosphazenes and surfactants including various anionic, cationic, and nonionic surfactants in aqueous solution. Most
of the anionic and cationic surfactants increased the LCST of the polymers: the LCST increased more sharply with increasing
length and hydrophobicity of the hydrophobic part of the surfactant molecule. The ΔLCSTs (T
0.03M − T
0M), the change in the LCST by addition of 0 and 0.03 M sodium dodecyl sulfate (SDS), were found to be 7.0 and 14.5 °C for the
polymers bearing ethyl esters of glycine and aspartic acid, respectively. The LCST increase of poly(organophosphazene) having
a more hydrophobic aspartic acid ethyl ester was 2 times larger compared with that of the polymer having glycine ethyl ester
as a side group. The binding behavior of SDS to the polymer bearing glycine ethyl ester as a hydrophobic group was explained
from the results of titration of the polymer solutions containing SDS with tetrapropylammonium bromide. Graphic models for
the molecular interactions of polymer/surfactant and polymer/surfactant/salt in aqueous solutions were proposed.
Received: 17 February 2000/Accepted: 25 April 2000 相似文献
10.
Irfan Ullah Musa Kaleem Baloch Gulrez Fatima Durrani 《Journal of solution chemistry》2012,41(2):215-222
The solubility of an anesthetic drug, LIDOCAINE, in water was investigated in the presence of ionic, nonionic and zwitterionic
surfactants at 25 °C, and the solubility was found to increase linearly with the surfactant concentration. The molar solubilization
ratio, R
m,s, and Gibbs free energy, DGso\Delta G_{\mathrm{s}}^{\mathrm{o}} values for nonionic surfactants fall in the order DDAO > Brij 35 > Brij 30, whereas for ionic and zwitterionic surfactants
the order is DDAPS > DTAB > SDS. The high negative values of the Gibbs energies in the cases of DDAO and DDAPS prove them
to be better surfactants for solubilizing this drug as compared to the other surfactants. 相似文献
11.
Maurice O. Iwunze 《Monatshefte für Chemie / Chemical Monthly》2000,269(1):429-435
Berberine hydrochloride is an alkaloid with little or no fluorescence in water. In sodium dodecylsulfate solutions, the fluorescence intensity of this compound is enhanced several folds by ion-pairing with the anion of the surfactant. The enhanced fluorescence intensity reaches a maximum at a surfactant concentration of 4·10−3 M and then decreases to a constant value at the critical micelle concentration and beyond. At concentrations near the maximum, a calibration sensitivity of 3.23·106/M was obtained. In addition, a good linear dynamic range and a low limit of detection (4·10−5 and 1.5·10−7 M, respectively) were determined. This observation indicates that this surfactant medium could be effectively used in fluorometric trace analysis of berberine hydrochloride. It was also observed in this work that solvents of low dielectric constant tend to stabilize this compound and thereby enhance its fluorescence. 相似文献
12.
Dhanaji S. Dalavi Meenatai J. Suryavanshi Sawanta S. Mali Dipali S. Patil Pramod S. Patil 《Journal of Solid State Electrochemistry》2012,16(1):253-263
In this paper, we report on the nickel oxide (NiO) thin films potentiostatically electrodeposited onto indium-doped tin oxide-coated
glass substrates by using two types of organic surfactants: (1) non-ionic: polyethylene glycol (PEG), polyvinylpyrrolidone
(PVP) and (2) anionic: sodium dodecyl sulfate (SDS). An aqueous solution containing nickel sulfate precursor and potassium
hydroxide buffer was used to grow the samples. The effect of organic surfactants on its structural, morphological, wettability,
optical, electrochromic, and in situ colorimetry were studied using X-ray diffraction, scanning electron microscopy, contact
angle, FT-IR spectroscopy, optical transmittance, cyclic voltammetry, and CIE system of colorimetry. X-ray diffraction patterns
show that the films are polycrystalline, consisting of NiO cubic phase. A nanoporous structure with pore diameter of about
150–200 nm was observed for pure NiO. The films deposited with the aid of organic surfactants exhibits various surface morphological
feature. PVP-mediated NiO thin film shows noodle-like morphology with well-defined surface area whereas, an ordered pore structure
composed of channels of uniform diameter of about 60–80 nm was observed for PEG. A compact and smooth surface with nanoporous
structure stem from SDS helps for improved electrochromic performance compared with that of NiO deposits from surfactant-free
solution. Wetting behavior shows, transformation from hydrophilic to superhydrophilic nature of NiO thin films deposited with
organic surfactant, which helps for much more paths for electrolyte access. The surfactant-mediated NiO produce high color/bleach
transmittance difference up to 57% at 630 nm. On oxidation of NiO/SDS, the CIELAB 1931 2° color space coordinates show the
transition from colorless to the deep brown state (L* = 84.41, a* = −0.33, b* = 4.41, and L* = 43.78, a* = 7.15, b* = 13.69), with steady decrease in relative luminance. The highest coloration efficiency of 54 cm2 C−1 with an excellent reversibility of 97% was observed for NiO/SDS thin films. 相似文献
13.
Maurice O. Iwunze 《Monatshefte für Chemie / Chemical Monthly》2000,131(5):429-435
Summary. Berberine hydrochloride is an alkaloid with little or no fluorescence in water. In sodium dodecylsulfate solutions, the fluorescence
intensity of this compound is enhanced several folds by ion-pairing with the anion of the surfactant. The enhanced fluorescence
intensity reaches a maximum at a surfactant concentration of 4·10−3 M and then decreases to a constant value at the critical micelle concentration and beyond. At concentrations near the maximum,
a calibration sensitivity of 3.23·106/M was obtained. In addition, a good linear dynamic range and a low limit of detection (4·10−5 and 1.5·10−7 M, respectively) were determined. This observation indicates that this surfactant medium could be effectively used in fluorometric
trace analysis of berberine hydrochloride. It was also observed in this work that solvents of low dielectric constant tend
to stabilize this compound and thereby enhance its fluorescence.
Received November 26, 1999. Accepted (revised) January 13, 2000 相似文献
14.
A series of hydrophobically modified polyacrylamide and polyacrylamide-co-poly(acrylic acid) gels with systematically varying hydrophobicity were prepared by free-radical polymerization of acrylamide,
n-alkylacrylamides (n = 10, 12, and 14), and acrylic acid. The swelling of these gels was examined in water and in both anionic and cationic surfactant
solutions. It was found that the gels which incorporated acrylic acid showed extremely high swelling in water. Maximum swelling
was observed in gels which incorporated 10 mol% acrylic acid. The swelling of these gels was much less in solutions of both
anionic and cationic surfactants than in water. The gels which did not incorporate acrylic acid demonstrated little swelling
in water, but showed increased swelling in both anionic and cationic surfactant solutions with increased hydrophobicity of
the gel.
Received: 1 February 1999 Accepted in revised form: 5 March 1999 相似文献
15.
1H NMR chemical shifts of solutions of the following cationic surfactants in D2O were determined as a function of their concentrations: cetyltrimethylammonium chloride, CTACl, a 1 : 1 molar mixture of
CTACl and toluene, cetylpyridinium chloride, CPyCl, cetyldimethylphenylam-monium chloride, CDPhACl, cetyldimethylbenzylammonium
chloride, CDBzACl, cetyldimethyl-2-phenylethylammonium chloride, CDPhEtACl, and cetyldimethyl-3-phenylpropylammonium chloride,
CDPhPrACl. Plots of observed chemical shifts versus [surfactant] are sigmoidal, and were fitted to a model based on the mass-action
law. Satisfactory fitting was obtained for the discrete protons of all surfactants. From these fits, we calculated the equilibrium
constant for micelle formation, K, the critical micelle concentration, CMC and the chemical shifts of the monomer, δmon and the micelle δmic. 1H NMR-based CMC values are in excellent agreement with those which we determined by surface tension measurements of surfactant
solutions in H2O, allowing for the difference in structure between D2O and H2O. Values of K increase as a function of increasing the size of the hydrophilic group, but the free energy of transfer per CH2 group of the phenylalkyl moiety from bulk water to the micellar interface is approximately constant, 1.9±0.1 kJ mol-1. Values of (δmic–δmon) for the surfactant groups at the interface, e.g., CH3–(CH2)15–N+(CH3)2 and within the micellar core, e.g., CH3–(CH2)15–N+ were used to probe the (average) conformation of the phenyl group in the interfacial region. The picture that emerges is
that the aromatic ring is perpendicular to the interface in CDPhACl and is more or less parallel to it in CDBzACl, CDPhEtACl,
and CDPhPrACl.
Received: 23 February 1996 Accepted: 29 August 1996 相似文献
16.
The possibilities of different media formed by lecithin/n-butanol (n-BuOH)/water ternary mixtures for the analysis of all-trans-retinol by fluorescence have been studied. Fluorescence intensity of retinol increases in the presence of different types
of aggregates formed in these media. Analytical features are good, the detection limit and quantification limit have micrograms
per liter levels, and the linear range and sensitivity are appropriate to determine retinol in cosmetic samples. The analysis
of retinol in anti-wrinkle creams can be achieved directly without any pretreatment of the sample. The vesicles built up from
a biocompatible surfactant (lecithin) in aqueous solution with a low amount of n-BuOH permit an appropriated media for a simple, rapid, and sensitive analytical method. This method has a linear range between
64.1 and 800 μg L−1, a sensitivity of 202.3 L mg−1, and a low detection and quantification limit at 19.2 and 64.1 μg L−1, respectively. 相似文献
17.
A survey of contamination of surface and drinking waters around Lake Maggiore in Northern Italy with polar anthropogenic environmental
pollutants has been conducted. The target analytes were polar herbicides, pharmaceuticals (including antibiotics), steroid
estrogens, perfluorooctanesulfonate (PFOS), perfluoroalkyl carboxylates (including perfluorooctanoate PFOA), nonylphenol and
its carboxylates and ethoxylates (NPEO surfactants), and triclosan, a bactericide used in personal-care products. Analysis
of water samples was performed by solid-phase extraction (SPE) then liquid chromatography–triple-quadrupole (tandem) mass
spectrometry (LC–MS–MS). By extraction of 1-L water samples and concentration of the extract to 100 μL, method detection limits
(MDLs) as low as 0.05–0.1 ng L−1 were achieved for most compounds. Lake-water samples from seven different locations in the Southern part of Lake Maggiore
and eleven samples from different tributary rivers and creeks were investigated. Rain water was also analyzed to investigate
atmospheric input of the contaminants. Compounds regularly detected at very low concentrations in the lake water included:
caffeine (max. concentration 124 ng L−1), the herbicides terbutylazine (7 ng L−1), atrazine (5 ng L−1), simazine (16 ng L−1), diuron (11 ng L−1), and atrazine-desethyl (11 ng L−1), the pharmaceuticals carbamazepine (9 ng L−1), sulfamethoxazole (10 ng L−1), gemfibrozil (1.7 ng L−1), and benzafibrate (1.2 ng L−1), the surfactant metabolite nonylphenol (15 ng L−1), its carboxylates (NPE1C 120 ng L−1, NPE2C 7 ng L−1, NPE3C 15 ng L−1) and ethoxylates (NPE
n
Os, n = 3-17; 300 ng L−1), perfluorinated surfactants (PFOS 9 ng L−1, PFOA 3 ng L−1), and estrone (0.4 ng L−1). Levels of these compounds in drinking water produced from Lake Maggiore were almost identical with those found in the lake
itself, revealing the poor performance of sand filtration and chlorination applied by the local waterworks. 相似文献
18.
Takashi Masadome 《Mikrochimica acta》2002,140(3-4):227-231
A cationic surfactant-selective electrode for sensitive analysis of cationic surfactants has been developed by using a plasticized
poly (vinyl chloride) membrane based on a hydrophobic cation exchanger, sodium tetrakis (3,5-bis(trifluoromethyl)phenyl) borate.
The electrode shows a Nernstian response to dodecyltrimethylammonium (DTA) ion in the concentration range from 8 × 10−7 M to 10−2 M with a slope of 55.3 ± 2.0 mV/decade. The electrode was used over a wide pH range of pH 2–12. The electrode is excellently
selective for the DTA ion over inorganic anions, but interferences of other cationic surfactants such as cetylpyridinium ion
and tetradecyldimethylbenzylammonium ion (zephiramine) are great.
The present electrode was applied to determine total cationic surfactants in commercial disinfectants.
Received February 27, 2002; accepted June 14, 2002 相似文献
19.
We present the phase diagrams and the properties of newly synthesised double-chain cationic N-alkyl-N-alkyl′-N,N-dimethylammonium bromide surfactants [C
x
C
y
DMABr (x = 12, 14 and 16; y = 10, 11, 12, 14 and 16)]. All the systems studied form liquid-crystalline lamellar phases but with different morphologies:
unilamellar vesicles at low surfactant concentrations, multilamellar vesicles and tubular aggregates for surfactant concentrations
between 2 and 10 wt% and at even higher concentrations planar bilayers of surfactant molecules in the classical Lα phase. The phase diagrams were determined with macroscopic and microscopic methods (polarisation microscopy, freeze-fracture
transmission electron microscopy, scanning electron microscopy and differential interference contrast microscopy). The properties
of the surfactant solutions were determined with differential scanning calorimetry measurements for Krafft point determination
and small-angle neutron scattering measurements for interlamellar spacing and bilayer thickness. Finally, conductivity and
viscosity measurements for phase characterisation were carried out.
Received: 7 April 1999 Accepted in revised form: 30 April 1999 相似文献
20.
The pH dependence of an anionic surfactant, sodium N-dodecanoylsarcosinate (SLAS), has been studied by measuring interfacial tension, fluorescence, dynamic light scattering,
etc., in aqueous solutions with phosphate and borate buffers. The interfacial tension (γ) of SLAS decreases remarkably with a pH decrease and is constant at pH > 7.3. The observed values for the critical micelle
concentration (cmc) and the surfactant concentration at which its γ value is reduced by 20 mN/m from that of pure water (C
20) decrease with a pH decrease, while those also become constant at pH > 6.5 and >7.3, respectively. On the other hand, the
interfacial excess of SLAS increases at pH < 7.3. These interfacial behaviors have been further investigated by the addition
of Tl+ which replaces Na+ of SLAS. The observed γ values of LAS− with the different counter cations are in the order of H+ < Tl+ < Na+. In order to reveal aggregation properties of SLAS, the aggregation number (N
agg), the micropolarity, the hydrodynamic radius (R
h) of micelle, and the fluorescence anisotropy of Rhodamine B (r) have been evaluated at various pHs. The N
agg value shows a decreasing tendency with a pH increase. The I
1/I
3 ratio and the R
h values do not strongly depend on pH. The r value decreases until pH 7 and remains constant at pH > 7.0. These interfacial and micelle properties have been discussed
in detail considering the electrostatic interaction and the molecular structures of the hydrophilic headgroup. 相似文献