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1.
RUB MalikAbdul ASIRIAbdullah M KUMAR Dileep AZUM Naved KHAN Farah 《物理化学学报》2014,30(4):699-707
The mixed micellization behavior of an amphiphilic antidepressant drug amitriptyline hydrochloride(AMT)in the presence of the conventional anionic surfactant sodium bis(2-ethylhexyl)sulfosuccinate(AOT)was studied at five different temperatures and compositions by the conductometric technique.The critical micelle concentration(cmc)and critical micelle concentration at the ideal state(cmcid)values show mixed micelle formation between the components(i.e.,drug and AOT).The micellar mole fractions of the AOT(X1)values calculated using the Rubingh,Motomura,and Rodenas models show a higher contribution of AOT in the mixed micelles.The interaction parameter(β)is negative at all temperatures and the compositions show attractive interactions between the components.The activity coefficients(f1and f2)calculated using the different proposed models are always less than unity indicating non-ideality in the systems.TheΔGmΘ values were found to be negative for all the binary mixed systems.However,ΔHmΘ values for the pure drug as well as the drug-AOT mixed systems are negative at lower temperatures(293.15-303.15 K)and positive at higher temperatures(308.15 K and above).TheΔSmΘ values are positive at all temperatures but their magnitude was higher at T=308.15 K and above.The excess free energy of mixing(ΔGex)determined using the different proposed models also explains the stability of the mixed micelles compared to the pure drug(AMT)and surfactant micelles. 相似文献
2.
The synergistic behavior of sodiumdodecylsulfate (SDS) and 1,2-diheptanoyl-sn-glycero-3-phosphocholine (DHPC) binary mixtures
has been studied with interfacial and pyrene fluorescence(I
1/ I
3) intensity measurements. From the interfacial data, the interfacial parameters; the maximum surface excess (Γmax), or the minimum area per molecule (A
min), and the surface pressure at the critical micellar concentration (πcmc) have been evaluated. The cmc value has been used for evaluating the free energies of micellization (ΔG
o
m). The mixed micelle formation was evaluated with the help of the Clint equation. The SDS plus DHPC mixed micelles showed
negative departure from ideality indicating synergistic interactions between the unlike components. The quantitative analysis
of mixed micelle, mixed monolayer and the composition of the mixed micelle was carried out with the help of regular solution
approximation. The interaction parameters, β and βσ, in the mixed micelle as well as in the mixed monolayer, respectively showed negative values indicating synergistic behavior
of SDS and DHPC molecules. 相似文献
3.
The interactions of non-ionic amphiphilic diblock copolymer poly(oxyethylene/oxybutylene)(E39B18) with anionic surfactant sodium dodecyl sulphate(SDS) and cationic surfactant hexadecyltrimethylammonium bromide(CTAB) were studied by using various techniques such as surface tension,conductivity,steady-state fluorescence and dynamic light scattering.Surface tension measurements were used to determine the critical micelle concentration(CMC) and thereby the free energy of micellization(△Gmic),free energy of adsorption(△Gads),surface excess concentration(Γ) and minimum area per molecule(A).Conductivity measurements were used to determine the critical micelle concentration(CMC),critical aggregation concentration(CAC),polymer saturation point(PSP),degree of ionization(α) and counter ion binding(β). Dynamic light scattering experiments were performed to check the changes in physiochemical properties of the block copolymer micelles taken place due to the interactions of diblock copolymers with ionic surfactants.The ratio of the first and third vibronic peaks(I1/I3) indicated the polarity of the pyrene micro environment and was used for the detection of micelle as well as polymer-surfactant interactions.Aggregation number(N),number of binding sites(n) and free energy of binding (△Gb) for pure surfactants as well as for polymer-surfactant mixed micellar systems were determined by the fluorescence quenching method. 相似文献
4.
Malik Abdul Rub Dileep Kumar Naved Azum Farah Khan Abdullah M. Asiri 《Journal of solution chemistry》2014,43(5):930-949
In the present paper, the micellization of an amphiphilic drug, promazine hydrochloride, and gemini surfactants (16-s-16) with s = 4–6 and the monomeric hexadecyltrimethylammonium bromide (CTAB) counterparts has been examined conductometrically in the pure and mixed states in aqueous solutions at different compositions and temperatures (298.15–308.15 K). Dicationic gemini surfactants provide much better environment for the micellization behavior than the corresponding monocationic counterpart CTAB. The critical micelle concentration (cmc) values are lower than the cmc for ideal mixing, cmc id, suggesting attractive interactions between the two components in mixed micelles. The micellar mole fractions of surfactants, evaluated by different models, show greater contributions of surfactants in mixed micelles and increase with increasing concentrations of these surfactants. The negative values of β suggest synergism in the mixtures, which is highly beneficial as it reduces the total amount of surfactants required in a particular application, leading to reductions of cost and environmental impact. Activity coefficients (f 1 and f 2) are always less than unity showing nonideality in the systems. The data have been also used for evaluation of thermodynamic parameters. 相似文献
5.
Naved Azum Malik Abdul Rub Abdullah M. Asiri Aftab Aslam Parwaz Khan Anish Khan Sher Bahadar Khan Mohammad M. Rahman Abdulrahman O. Al-Youbi 《Journal of solution chemistry》2013,42(7):1532-1544
Pyrene fluorescence measurements were carried out on various binary mixtures of the antidepressant amphiphilic drug amitriptyline hydrochloride (AMT) with conventional (TTAB and CTAB) and gemini surfactants (14-4-14 and 16-4-16). In all cases mixed micellar aggregates were formed and the mixed critical micelle concentration (cmc) of various mixtures was computed from the I 1/I 3 versus total surfactant concentration plots. In the region where mixed micelles are formed, the interaction of the amphiphlic drug and four surfactants showed synergistic behavior. The results were analyzed using an interaction parameter, β, which characterize the interaction in the mixed micelle and is introduced by a regular solution theory. The β values are negative in all binary mixtures, and their magnitudes increase with increasing hydrophobicity of the amphiphile. The micellar mole fraction of AMT in the mixed micelle (x 1) and in the ideal sate (x ideal) were evaluated and their values (x 1 > x ideal) suggest that the contribution of the AMT component is greater in binary mixtures as compared to that in the ideal state. Activity coefficients (f 1 and f 2) and excess Gibbs energy (G ex) were also calculated. The values of micelle aggregation numbers (N agg) and various other parameters like the Stern–Volmer constant (K sv), micropolarity and dielectric constant of mixed systems have also been evaluated from the ratios of respective peak intensities (I 1/I 3 or I 0/I 1). 相似文献
6.
Cyclic voltammetry has been employed to investigate the mixed micellar behavior of the binary mixtures of different zwitterionic surfactants such as 3-(N,N-dimethylhexadecylammonio)propane sulfonate (HPS), 3-(N,N-dimethyltetradecylammonio)propane sulfonate (TPS) and 3-(N,N-dimethyldodecylammonio)propane sulfonate (DPS) with three triblock polymers (L64, F127 and P65) by using 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) as an electroactive probe at 25 °C. Critical micellar concentration (cmc) has been determined from the plots of variation in peak current (ip) versus the total concentration of surfactant/triblock polymer. Diffusion coefficient of the electroactive species has also been reported. The regular solution theory approximation has been used to determine various micellar parameters of ideal systems. The variation in micellar mole fraction (X1) of the zwitterionic surfactant supports the formation of mixed micelles, which are rich in triblock polymer component in the surfactant rich region of the mixture and vice versa. The regular solution interaction parameter (β) suggests the formation of mixed micelles due to the synergistic interactions in case of HPS/TPS/DPS + F127/P65 systems and gets affected by EO/PO ratio of triblock polymers. 相似文献
7.
Surface active micelle formable surfactant-Cr(III) complexes of the type cis-α-[Cr(trien)(C16H33NH2)X]2+ (where trien = triethylenetetramine; X = F−, Cl−, Br−) have been studied in n-alcohol and in formamide at different temperatures by conductance measurements. Standard Gibbs energy changes (ΔG
o
mic), enthalpies (ΔH
o
mic) and entropies (ΔS
o
mic) of micelle formation have been determined by studying the variation of the Critical Micelle Concentration (CMC) with temperature.
Critical micelle concentrations have also been measured as a function of percentage concentration of alcohol added. It is
suggested that alcohol addition leads to an increase in formamide penetration into the micellar interface that depends on
the alcohol chain length. The results are discussed in terms of an increased hydrophobic effect, dielectric constant of the
medium, the chain length of the alcohols and the surfactant in the solvent mixture. 相似文献
8.
Arpita Sahu Soumyadip Choudhury Achinta Bera Shranish Kar Sunil Kumar 《Journal of Dispersion Science and Technology》2013,34(8):1156-1169
The interactions between an anionic surfactant, viz., sodium dodecylbenzenesulfonate and nonionic surfactants with different secondary ethoxylated chain length, viz., Tergitol 15-S-12, Tergitol 15-S-9, and Tergitol 15-S-7 have been studied in the present article. An attempt has also been made to investigate the effect of ethoxylated chain length on the micellar and the thermodynamic properties of the mixed surfactant systems. The micellar properties like critical micelle concentration (CMC), micellar composition (XA), interaction parameter (β), and the activity coefficients (fA and fNI) have been evaluated using Rubingh's regular solution theory. In addition to micellar studies, thermodynamic parameters like the surface pressure (ΠCMC), surface excess values (ΓCMC), average area of the monomers at the air–water interface (Aavg), free energy of micellization (ΔGm), minimum energy at the air–water interface (Gmin), etc., have also been calculated. It has been found that in mixtures of anionic and nonionic secondary ethoxylated surfactants, a surfactant containing a smaller ethoxylated chain is favored thermodynamically. Additionally, the adsorption of nonionic species on air/water interface and micelle increases with decreasing secondary ethoxylated chain length. Dynamic light scattering and viscometric studies have also been performed to study the interactions between anionic and nonionic surfactants used. 相似文献
9.
10.
HAO ChangChun SUN RunGuang ZHANG Jing CHANG YiGuang & NIU ChunLing College of Physics Information Technology Shaanxi Normal University Xi’an China College of Food Engineering Nutritional Science 《中国科学B辑(英文版)》2009,52(2):219-225
Lipid rafts are of a dynamic microdomain structure found in recent years,enriched in sphingolipids,cholesterol and particular proteins.The change of structure and function of lipid rafts could result in many diseases.In this work,the monolayer behavior of mixed systems of D-sphingosine with choles-terol was investigated in terms of the mean surface area per molecule(Am),excess molecular area(Aex),surface excess Gibbs energy(Gex),interaction parameter(ω),activity coefficients(1 and 2) as well as elasticity(C... 相似文献
11.
Mixed micelle formation and surface tension reduction effectiveness (γcmc) were investigated for the following systems: triethanolammonium dodecylpoly(oxyethylene)sulfate (TADPS, containing about
two ethylene oxide units)/dodecyltrimethylammonium bromide, TADPS/hexadecyltrimethylammonium bromide and TADPS/hexadecylpyridinium
chloride. For all these anionic/cationic systems, the mixed critical micelle concentration (cmc) values reflect a strong synergism
in mixed micelle formation, with βM values ranging from −13.8 to −18.3. The mixed micelle composition is mixing-ratio dependent and, for equimolar mixtures,
the mixed micelle is richer in the surfactant with the lower cmc. Precipitation is inhibited to a certain extent, thanks to
the presence of ethylene oxide groups in the anionic species. The conditions for synergism in γcmc, differently expressed in the literature, can be derived from the surface tension equations established in our previous article.
They can be conveniently described by a few characteristic constants: Γ
i
∞ (saturated Gibbs excess), K
i
(constant in the Szyszkowski equation), the cmc of the individual surfactants and the interaction parameters, βS and βM, of their mixtures. Excellent agreement between theoretically predicted and experimental results is obtained. With the increase
in surfactant chain length, the βM values decrease faster than the βS ones and this can result in the loss of synergism in γcmc.
Received: 11 June 2000 Accepted: 4 September 2000 相似文献
12.
13.
Narayanasamy Kumaraguru Sankarlingam Arunachalam Mahadevimanglam Narayanasamy Arumugham Kannappan Santhakumar 《Transition Metal Chemistry》2006,31(2):250-255
A number of mixed ligand chromium(III)–surfactant coordination complexes, of the type cis-[Cr(en)2(A)X]2+ and cis-α-[Cr(trien)(A)X]2+ (A = Dodecyl or Cetylamine; X = F−, Cl−, Br−) were synthesized from the corresponding dihalogeno complexes by ligand substitution. These compounds form foam in aqueous
solution when shaken. The critical micelle concentration (CMC) values of these surfactant metal complexes in aqueous solution
were obtained from conductance measurements. Specific conductivity data (at 303, 308 and 313 K) served for evaluation of the
temperature-dependent critical micelle concentration (cmc) and the thermodynamics of micellization (Δ Gm0, Δ Hm0 and Δ Sm0). 相似文献
14.
The micellization behavior of an anionic gemini surfactant, GA with nonionic surfactants C12E8 and C12E5 in presence of 0.1 M NaCl at 298 K temperature, has been studied tensiometrically in pure and mixed states, and the related
physicochemical parameters (cmc, γ
cmc, pC
20, Γ
max, and A
min) have been evaluated. Tensiometric profile (γ vs log [surfactant]), for conventional surfactants, generally consists of a single point of intersection; a gradually decreasing
line (normally linear, or with slight curvature) ultimately saturates in γ at a particular [surfactant], corresponding to complete monolayer saturation. The gemini, in this report, led to two unequivocal
breaks in the tensiometric isotherm. An attempt to the interpretation of the two breaks from molecular point of view is provided,
depending solely on the chemical structure of the surfactant. The gemini, even in mixed state with the conventional nonionic
surfactants C12E5 and C12E8, manifested the dual breaks; of course, the dominance of the feature decreases with increasing mole fraction of the nonionics
in the mixture. Theories of Clint, Rosen, Rubingh, Motomura, Georgiev, Maeda, and Nagarajan have been used to determine the
interaction between surfactants at the interface and micellar state of aggregation, the composition of the aggregates, the
theoretical cmc in pure and mixed states, and the structural parameters according to Tanford and Israelachvili. Several thermodynamic
parameters have also been predicted from those theories. 相似文献
15.
Hong-Lin Zhang Zhe Kong Yong-Mei Yan Gan-Zuo Li Li Yu Fei Geng 《Journal of solution chemistry》2008,37(12):1631-1644
The power-time curves for the micelle formation process were determined for two anionic surfactants, sodium laurate (SLA)
and sodium dodecyl sulfate (SDS), in mixed alcohol + N,N-dimethylacetamide (DMA) solvent using titration microcalorimetry.
From the data of the lowest point and the area of the power-time curves, their critical micelle concentration (CMC) and ΔH
mo were obtained. The other thermodynamic functions of the micellization process (ΔG
mo and ΔS
mo) were also calculated with thermodynamic equations. For both surfactants, the effects of the carbon number (chain length)
of the alcohol, the concentration of alcohol, and the temperature on the CMC and thermodynamic functions are discussed. For
systems containing identical concentrations of a different alcohol, values of the CMC, ΔH
mo and ΔS
mo increased whereas ΔG
mo decreased with increasing temperature. For systems containing an identical alcohol concentration at the same temperature,
values of the CMC, ΔH
mo,ΔG
mo and ΔS
mo decrease with increasing carbon number of alcohol. For systems containing the same alcohol at the same temperature, the CMC
and ΔG
mo values increase whereas ΔH
mo and ΔS
mo decrease with increasing alcohol concentration. 相似文献
16.
《高分子科学杂志,A辑:纯化学与应用化学》2013,50(5-6):697-718
The conductances of hexadecyltrimethylammonium bromide (HTAB) + tetradecyltrimethylammonium bromide (TTAB) mixtures over the entire mole fraction range of HTAB (αHTAB) were measured in pure water as well as in the presence of various aqueous ethylene glycol oligomers containing 5, 10 and 20 wt% of each additive in their respective binary mixtures at 30°C. From the conductivity data, the critical micellar concentration (cmc), degree of counter ion association (χ) and the standard free energy of transfer of the surfactant hydrocarbon chain from the medium to the micelle (ΔGO HP ) for HTAB and TTAB were computed. From the conductivity data of mixed surfactants systems, apart from cmc and χ, the regular solution theory parameters were also computed in order to explore the non-ideality in the mixed micelle formation in the presence of additives. The micellar parameters of both kind of surfactants and their mixtures show a significant dependence on the amount as well as on the number of repeating units of glycol oligomers. However, the non-ideality of mixed micelle formation remains unaffected in the presence of additives. These results have been explained on the basis of the medium effects of aqueous additive and it has been concluded that there are no significant interactions of glycol oligomers with the micelles of single and mixed surfactants. 相似文献
17.
18.
Galán J. J. González-Pérez A. Rodríguez J. R. 《Journal of Thermal Analysis and Calorimetry》2003,72(2):465-470
Specific conductivity of aqueous solutions of dodecyldimethylethylammonium bromide has been determined in the temperature
range of 15-40°C. The critical micelle concentration (cmc) and ionization degree of the micelles, b, were determined from
the data. Thermodynamic functions, such as standard Gibbs free energy, ΔG
m°, enthalpy, ΔG
m°, and entropy, ΔG
m°, of micellization, were estimated by assuming that the system conforms to the mass action model. The change in heat capacity
upon micellization, ΔG
m°, was estimated from the temperature dependence of ΔG
m°. An enthalpy-entropy compensation phenomenom for the studied system has been found.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
19.
N. Kumaraguru K. Santhakumar S. Kalyanasundharam 《Journal of solution chemistry》2011,40(10):1673-1686
The critical micelle concentration (CMC) of surfactant–Cr(III)–dodecylamine complexes of the type cis-α-[Cr(trien)(C12H25NH2)X]2+ (where trien = triethylenetetramine; X = F−, Cl−, Br−) has been studied in n-alcohol and in formamide at different temperatures, by electrical conductivity measurements. From the CMC values as a function
of temperature, various thermodynamic properties have been evaluated: standard Gibbs energy changes (Δmic
G
0), standard enthalpy changes (Δmic
H
0) and standard entropy changes (Δmic
S
0) for micellization. Critical micelle concentrations have also been measured as a function of the percentage composition of
alcohol added. The solvent composition dependences of these thermodynamic parameters were determined. It is suggested that
alcohol addition leads to an increase in formamide penetration into the micellar interface that depends on the alcohol’s chain
length. The results are discussed in terms of an increased hydrophobic effect, dielectric constant of the medium, the chain
length of the alcohols, and the surfactant in the solvent mixture. 相似文献
20.
Elena Blanco J. M. Ruso J. Sabín G. Prieto F. Sarmiento 《Journal of Thermal Analysis and Calorimetry》2007,87(1):211-215
The interactions of lysozyme and myoglobin with anionic surfactants
(hydrogenated and fluorinated), at surfactant concentrations below the critical
micelle concentration, in aqueous solution were studied using spectroscopic
techniques. The temperature conformational transition of globular proteins
by anionic surfactants was analysed as a function of denaturant concentration
through absorbance measurements at 280 nm. Changes in absorbance of protein-surfactant
system with temperature were used to determine the unfolding thermodynamics
parameters, melting temperature, T
m,
enthalpy, ΔH
m,
entropy, ΔS
m
and the heat capacity change, ΔC
p,
between the native and denatured states. 相似文献