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1.
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   

2.
Relationship for predicting Logcmc for cationic surfactants having chloride as counterion from only molecular connectivity indices was found. It is suggested that the index 0χν includes some information about hydrophobicity while indices 4χ pc and 4cnpc{^{4}\chi^{\nu}_{pc}} include some information about hydrophilicity of the cationic surfactants studied. The structures of 23 compounds used for the correlation are quite diverse.  相似文献   

3.
A series of novel cationic gemini surfactants, p-[C n H2n+1N+(CH3)2CH2CH(OH)CH2O]2C6H4·2Cl? [A(n = 12), B(n = 14) and C(n = 16)], containing a spacer group with two flexible and hydrophilic groups (2-hydroxy-1,3-propylene) on both sides of a rigid and hydrophobic group (1,4-dioxyphenylene) has been synthesized by the reaction of hydroquinone diglycidyl ether with N,N-dimethylalkylamine and N,N-dimethylalkylamine hydrochloride. Their surface-active properties have been investigated by surface tension measurement. The critical micelle concentration (cmc) values of the synthesized cationic gemini surfactants are one order of magnitude lower than those of their corresponding monomeric surfactants (C n H2n + 1N+(CH3)3·Cl?). Both the cmc and surface tension at the cmc (γcmc) of A are lower than those of p-[C12H25N+(CH3)2CH2]2C6H4·2Cl? (D). The novel cationic gemini surfactants A and B also show good foaming properties.  相似文献   

4.
5.
6.
A novel bicaudate gemini surfactant was synthesized with anhydrous piperazine, chloride- bian, and 1-bromo dodecane as raw materials. Its structure was verified by infrared and 1H NMR. The surface active properties of the bicaudate gemini surfactant in water were measured at 55°C. Its critical micelle concentration (cmc) and γ cmc was 0.50 mmol · L?1 and 28.95 mN · m?1, respectively. Results indicate that there was not a remarkable difference in γcmc values between the synthesized bicaudate surfactant and conventional gemini surfactant N,N′–bis (dodecyl dimethyl ammonium bromide)-3-oxa-1,5-pentadiammonium. The sterilizing antimicrobial performance of the bicaudate gemini surfactant was examined. The bicaudate gemini surfactant show excellent inhibition against 18 types of bacteria compared with conventional monomeric surfactant and gemini surfactant at concentrations of 50 mg/L.  相似文献   

7.
A series of dissymmetric gemini imidazolium surfactants with different spacer length ([CmCsCnim]Br2, m + n = 24, m = 12, 14, 16, 18; s = 2, 4, 6) were synthesized and characterized by 1H NMR and ESI-MS spectroscopy. Their adsorption and thermodynamic properties were investigated by the surface tension and electrical conductivity methods. Consequently, the surface activity parameters (cmc, γcmc, πcmc, pC20, cmc/C20, Γmax, Amin) and thermodynamic parameters (ΔGmθ, ΔHmθ, ΔSmθ) were obtained. The effects of the dissymmetry (m/n) and the spacer length (s) on the surface activity and micellization process of surfactants have been discussed in detail.  相似文献   

8.
The synthesis of surfactants derivatives of new two series of cationic gemini surfactants containing ethane or benzene as a spacer are described. The prepared compounds were analyzed using standard tools of analysis, elemental analysis, FTIR measurements, and H1 NMR spectra. The influence of dimerization and of the spacer group were examined in order to establish structure-property relationships. The critical micelle concentration (CMC) of each series has been determined using equilibrium surface tension measurements. Furthermore, air/water interface parameter including effectiveness (Πcmc), efficiency (P20), maximum surface excess (τmax), and minimum surface area (Amin) have been also derived using Gibbs adsorption equation at 25°C. Standard free energies of micelleization were calculated and biological activities were examined. The results revealed that the dimeric surfactants have a good effect on the biological activities.  相似文献   

9.
A theory of cationic dimeric (gemini) surfactant adsorption onto negatively charged surface is presented. In the proposed model it is assumed that the adsorbed phase is a mixture of singly dispersed molecules of surfactant and spherical, globular and cylindrical aggregates of different dimensions. Only the “excluded area” interactions between the adsorbed species are considered and the effects of surface heterogeneity on monomer adsorption are taken into account. The aggregation behavior of gemini surfactants is based on the additive free energy model proposed by Camesano and Nagarajan (2000). The calculated surfactant adsorption isotherms and the differential molar enthalpies of micellisation and adsorption are compared with the experimental results obtained for a series of gemini surfactants depending on the length of a spacer, temperature or the presence of electrolyte. On the basis of theoretical results the evolution of adsorbed phase of gemini surfactants with the increasing adsorption is discussed. It is shown that the evaluated cmc values and the dimensions of surfactant aggregates are in a good agreement with experiment. Unfortunately, the theoretical model does not describe properly the temperature dependence of micellisation process.  相似文献   

10.
The interaction between β-cyclodextrin (β-CD) and an amino acid-based anionic gemini surfactant derived from cysteine (C8Cys)2 was studied by three independent techniques: electrical conductivity, UV–Vis spectral displacement technique using phenolphthalein as probe, and 1H NMR spectroscopy. The data obtained indicated the formation of a 1:1 inclusion complex between β-CD and the gemini surfactant studied and allowed for the determination of the binding constant, K1, by considering this stoichiometry. Electrical conductivity, spectral displacement technique, and NMR chemical shift measurements, obtained for aqueous β-CD–surfactant systems, yielded consistent K1 values in the order of 102 dm3 mol?1, typical of a weakly bound β-CD–surfactant complex. The influence of the presence of the inclusion complex on the micellization process of the gemini surfactant has also been studied and the apparent critical micelle concentration (cmc1) has been obtained. Increasing β-CD concentration was found to shift the cmc1 to higher values, as complexed surfactant monomers are not available to form micelles and aggregation takes place only when all β-CD cavities are occupied.  相似文献   

11.
The properties of diflunisal, a widely used analgesic, were studied in physiologic solutions, 0.15 mol·dm?3 NaCl. Solubility and protonation constants were determined and its behavior as ligand towards Ca(II) and Mg(II) was investigated. Solubility and protonation constants of diflunisal at 25 °C and 0.15 mol·dm?3 were obtained from electromotive force measurements of galvanic cells using coulometric titrations. The experimental data yielded the solubility, s, of –log10 s = 3.86 ± 0.02 and the protonation constants log10 K 1 = 11.98 ± 0.10 and log10 K 2 = 3.86 ± 0.03. Equilibria between diflunisal and Ca(II) and Mg(II) were investigated by means of electromotive force measurements and by comparing solubilities of diflunisal in the presence and absence of Ca(II) or Mg(II), respectively. Experimental data were explained by assuming the formation of 1:1 complexes for Ca(II) and Mg(II) along with evaluating the relative stability constants.  相似文献   

12.
Using surface tension and fluorescence methods, the surface and solution properties of two cationic gemini surfactants {pentanediyl-1,5-bis(dimethylcetylammonium bromide) and hexanediyl-1,6-bis(dimethylcetylammonium bromide)} (referred to as 16-5-16 and 16-6-16) have been studied in the presence and absence of primary linear alkanols. Parameters studied include the critical micelle concentration (CMC), C 20 (the surfactant concentration required to reduce the surface tension of the solvent by 20 mN·m?1), Г max (maximum surface excess), and A min (minimum surface area per molecule). These parameters indicate mixed micelle formation and, therefore, surfactant-additive interaction parameters in mixed micelles and mixed monolayers, as well as activity coefficients, were calculated. A synergistic effect was observed in all instances and was found to be correlated with the chain length of the alkanols. The CMC values of 16-s-16 (s = 5, 6) decrease with increasing alkanol concentration and the extent of this effect follows the sequence: 1-octanol (C8OH) > 1-heptanol (C7OH) > hexan-1-ol (C6OH) > 1-pentanol (C5OH) > butanol (C4OH). The micelle aggregation number (N agg) of mixed micelles has been obtained using the steady state fluorescence quenching method. The micropolarity of gemini/alkanol systems has been evaluated from the ratio of intensity of peaks (I 1/I 3) of the pyrene fluorescence emission spectra. Results are interpreted on the basis of the structure of mixed micelles and monolayers.  相似文献   

13.
Well-ordered hexagonal mesoporous tungsten trioxide with crystalline pore walls were synthesized at low hydrothermal temperature by using cationic quaternary ammonium gemini surfactants as structure-directing agents and sodium tungstate dihydrate (Na2WO4·2H2O) as a precursor. The effects of alkyl chain length of gemini surfactants, hydrothermal temperature and molar ratio of tungsten to gemini surfactants have been investigated in detail. The strong self-assembly ability of gemini surfactants, strong electrical interaction between gemini surfactants and tungsten trioxide, and solvent extraction strategy contributed together to the coexistence of WO3 mesostructures and crystalline pore walls.  相似文献   

14.
The partitioning behavior of four newly synthesized chalcones between aqueous and micellar phases of ionic surfactants (SDS and CTAB) was investigated using ultraviolet-visible spectroscopy. The simple absorption spectra were recorded to study the interaction between these drugs and surfactants (in the concentration range below critical micelle concentration to above critical micelle concentration). The absorption data is also used to determine the number of additive molecules incorporated per micelle of the surfactant. The partition coefficient (Kx) of additives between bulk water phase and the micellar phase was determined in the range of 5.52 × 10+4 to 5.06 × 10+5 at 298 K by differential spectroscopic method. The corresponding standard free energy of partition ΔG°p obtained was in the range of ?27.05 kJmol?1 to ?32.54 kJmol?1. The relative solubility of additives between aqueous and micellar phases in different micellar concentrations was also estimated. The results showed that the chalcones are preferably soluble in cationic surfactant micelles.  相似文献   

15.
The goal of this paper is to estimate the number of realistic drug-like molecules which could ever be synthesized. Unlike previous studies based on exhaustive enumeration of molecular graphs or on combinatorial enumeration preselected fragments, we used results of constrained graphs enumeration by Reymond to establish a correlation between the number of generated structures (M) and the number of heavy atoms (N): logM = 0.584 × N × logN + 0.356. The number of atoms limiting drug-like chemical space of molecules which follow Lipinsky’s rules (N = 36) has been obtained from the analysis of the PubChem database. This results in M ≈ 1033 which is in between the numbers estimated by Ertl (1023) and by Bohacek (1060).  相似文献   

16.
The present research work is associated with the fluorescence investigations of binary aqueous mixed surfactants solutions of anionic bis-sulfosuccinate gemini surfactant (BSGSMA1,8) and three different conventional surfactants—anionic viz. sodium dodecyl sulfate (SDS), cationic viz. cetyl trimethyl ammonium bromide (CTAB), and nonionic surfactant viz. Triton X 100. Steady-state fluorescence spectroscopy technique has been utilized to examine the micellization behavior of aqueous solution of pure myristyl alcohol-based BSGSMA1,8 having flexible methylene chain [(CH2)8] as spacer group. Critical micelle concentration (CMC), aggregation number (N), and micropolarity of pure and mixed surfactants systems were explored during the investigations. The results revealed the best synergism behavior of prepared gemini BSGSMA1,8 with SDS as compared to CTAB and Triton X 100. The maximum reduction in the value of pyrene intensity ratio (I1/I3) was observed for gemini and SDS mixed surfactant solution. On the other hand, the increased I1/I3 value of mixed gemini with Triton X 100 exhibited that mixed surfactant system of anionic gemini BSGSMA1,8 with non-ionic Triton X 100 is not as compact as other mixed surfactant systems. Aggregation number increased and micropolarity decreased with increased concentration of gemini surfactants.  相似文献   

17.
18.
N-hydroxyethyl-3-alkyloxypyridinium amphiphiles have been synthesized and characterized by various spectroscopic techniques. Self-assembling properties of these amphiphiles have been studied by surface tension, conductivity, and fluorescence measurements. Basic micellization parameters like critical micelle concentration (cmc), surface tension at the cmc (γ cmc), adsorption efficiency (pC20), effectiveness of surface tension reduction (Π cmc), maximum surface excess concentration (Γ max) and minimum surface area/molecule (A min), and Gibbs free energy of the micellization (ΔG0 mic) have also been determined. The micellization of these 3-alkyloxypyridinium halides in aqueous phase have been found to be exothermic and entropy-driven as assessed by conductivity measurements at different temperatures. Thermal degradation of these surfactants has also been assessed by thermal gravimetric analysis under nitrogen atmosphere. Further, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay of these surfactants on C6 glioma cells show them to be less toxic than conventional cationic surfactants.  相似文献   

19.

Micellization behavior of cationic monomeric surfactants, hexadecyltrimethylammonium bromide (CTAB), cetylpyridinium bromide (CPB), cetylpyridinium chloride (CPC), tetradecyltrimethylammonium bromide (TTAB), and dimeric (gemini) cationic surfactant pentamethylene‐1, 5‐bis(hexadecyldimethylammonium bromide) with formula C16H33(CH3)2N+(CH2)5N+(CH3)2C16H33 · 2Br?, abbreviated as 16‐5‐16, in mixed states (binary) have been studied by conductivity. The micellar compositions, activities of the components, and their mutual interactions have been estimated from Rubingh's theory. The mixtures show nonideal behavior with favorable interactions.  相似文献   

20.
Five kinds of dual hydroxyl sulfobetaines with different carbon atom numbers in hydrophobic chain were synthesized by using linear saturated alcohol, epichlorohydrin and dimethylamine, and then their structures were characterized by FTIR and 1H NMR. The stability of all synthesized betaine surfactants in hard water was at level 4, which indicated they had high tolerance on hard water. Their CMC and γcmc were lower than the conventional cationic surfactant dodecyltrimethylammonium bromide and anionic surfactant sodium dodecyl, so they had more excellent surface activities. With the chain length increasing from C8 to C14, the surface activities, emulsifying properties and foaming properties of these betaine surfactants improved because surfactant molecules tightly arranged in the oil-water interface, but there was abnormal phenomenon of surface activity and foam property from C14 to C16 due to overlong hydrophobic chain. According to the results of the experiment, C14SB was the most practical in the five kinds of surfactants, which was potential candidate to enhance oil recovery in oil field. The performances of C14SB were as follows: CMC?=?2.2?×?10?4?mol/L, γcmc?=?30.9 mN/m and the time of bleeding 10?mL water t?=?375?s at 2?g/L the optimum emulsification concentration.  相似文献   

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