Critical Micelle Concentration Of Mixtures Research Articles

Design of diversified self-assembly systems based on a natural rosin-based tertiary amine for doxorubicin delivery and excellent emulsification.

A novel rosin-based ester tertiary amine (RETA) with three hydrophilic groups and a rigid hydrophobic group was synthesized from rosin by Diels-Alder addition, acylation and esterification reactions. RETA was characterized by infrared spectroscopy (FT-IR) and proton nuclear magnetic resonance spectroscopy (13C NMR). Results from testing surface tension, zeta potential, and transmission electron spectroscopy showed that RETA had unique pH responsiveness. RETA self-assembled into worm-like micelles, spherical micelles 130 nm in diameter and big spherical worm-like aggregates with diameter of 2 μm at pH = 5.76, 8.04 and 9.38, respectively. The critical micelle concentration (CMC) of RETA was 0.42 mmol/L, and the surface tension at CMC (γcmc) was 38.73 mN/m when pH was 8.04. The RETA had a potential application in delivering doxorubicin hydrochloride (DOX) due to the pH responsiveness. Self-assembly mixed systems of RETA and rosin-based phosphoric acid (DDPD) were designed to improve emulsification. The mixed systems had obvious synergistic effects and unexpected emulsification. The γcmc and CMC of mixtures were 41.74 mN/m and 0.20 mmol/L, the size of mixture micelles increased up to 300 nm in the optimum molar ratio of RETA/DDPD (7:3) by TEM and cryo-TEM. It was worth noting that the mixture system formed vesicles in the RETA/DDPD molar ratio of 5:5. The stability time of emulsion with RETA and DDPD as emulsifier were only 63 s and 52 s respectively, but the stability time increased to 234 s in the optimum molar ratio. In addition, the formation mechanisms of micelles at different pH and in various mixtures were discussed in detail. What's more, cytotoxicity results showed that the toxicity of RETA was lower significantly than that of lecithin, a food ingredient in egg yolk and soybean. The cell viability was more than 83% in the high concentration of RETA (4000 μg/ml).

Synthesis, surface, biological activity and mixed micellar phase properties of some biodegradable gemini cationic surfactants containing oxycarbonyl groups in the lipophilic part

Three biodegradable gemini cationic surfactants were synthesized and namely: N,N′-bis(2-hydroxyethyl)-N,N′-dimethyl-N,N′-bis(2-(tetradecanoyloxy) ethyl)ethane-1,2-diaminium bromide; N,N′-bis(2-hydroxyethyl)-N,N′-dimethyl-N,N′-bis(2-(tetradecanoyloxy) ethyl) hexane-1,6-diaminium bromide and N,N′-bis(2-hydroxyethyl)-N,N′-dimethyl-N,N′-bis(2-(tetradecanoyloxy) ethyl)dodecane-1,12-diaminium bromide. The chemical structures of these compounds were characterized by FTIR, 1H NMR and elemental analysis spectroscopy. The surface parameter including: the critical micelle concentration (CMC), effectiveness (πcmc), efficiency (Pc20), maximum surface excess (Γmax) and minimum surface area (Amin), were calculated from it is surface tension measurements. The synthesized surfactants showed higher surface activity. The thermodynamic parameters showed that adsorption and micellization processes are spontaneous. It is clear that the synthesized surfactants showed their tendency towards adsorption at the interfaces and also micellization in the bulk of their solutions. The synthesized compounds were applied on the field of biocide via measuring there efficiency against different strain of pathogenic bacteria and fungi as well as sulfate reducing bacteria using inhibition zone diameters method and minimum inhibition concentration values. The synthesized compounds showed good antimicrobial activities against the tested microorganisms including Gram positive, Gram negative and fungi as well as sulfate reducing bacteria. The biodegradability of the synthesized surfactants was tested in river water using Die-away method and showed their readily biodegradation in the open environment. The CMC of mixtures in equal mole fraction (G2+G6 (5:5), G2+G12 (5:5), G6+G12 (5:5)) and the CMC of mixtures was compared with pure gemini surfactants. Also the mixed micellization parameters were calculated.

Surface Properties of Gleditsia Saponin and Synergisms of Its Binary System

A gleditsia saponin (GS) is isolated and purified from the fruits of Gleditsia sinensis Lam. Its surface and thermodynamic properties in aqueous solution at 0, 15, 25, 35, 45, and 60°C have been investigated by surface tension measurement. The major data at 25°C are the critical micelle concentration (cmc), 1.10E‐3 mol · L−1; the surface tension at cmc (γ cmc ), 34.4 mN · m−1; the maximum surface excess concentration (Γmax), 2.33E‐6 mol · m2; the minimum area per molecule (A cmc ), 0.712 nm2; the standard adsorption energy (ΔG ad 0), −32.9 kJ · mol−1; and the standard micellization energy (ΔG m 0), −16.9 kJ · mol−1. The molecular interaction parameters, β s and β m , for the binary systems of GS with a cationic surfactant (C16H33NMe3Br), an anionic surfactant (C12H25SO3Na), and a nonionic surfactant (C8H17Ph(EO)10OH) have been determined. Based on the regular solution treatments of Rubingh, Rosen, and their coworkers, the conditions of synergism in surface tension reduction effectiveness have been extended. The condition to produce this synergism and the corresponding parameters at the maximum synergism point, i.e., the mole fractions of surfactant 1 in the solution phase (α1*), the critical micelle concentration of mixtures (cmc 12*), and the surface tension at this concentration (γ cmc12*), are given. The results show that of the three binary systems, synergism in micelle formation can occur only in the mixture of GS with cationic surfactants; synergism in surface tension reduction efficiency can occur in the mixture of GS with both cationic surfactant and nonionic surfactants, but, all the binary systems of GS with ionic and nonionic surfactants can show remarkable synergism in surface tension reduction effectiveness.

Preparation and dilute solution properties of model gemini nonionic surfactants

Dimeric poly(ethylene oxide) surfactants (or nonionic gemini surfactants) with the structure (C n−2 H 2 n−3 CHCH 2O(CH 2CH 2O) m H) 2(CH 2) 6 (or Gem n E m ), 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 °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.

MICELLE FORMATION IN MIXTURES OF ANIONIC AND NONIONIC SURFACTANTS

ABSTRACT The critical micelle concentration of mixtures of anionic and nonionic surfactants was measured. The anionic surfactants were alkylbenzene sulfonates and the nonionic surfactants were polyoxyethylene nonylphenols and a polyoxy-ethylene alcohol. The effect of added electrolyte, the number of ethylene oxide units in the polyethoxylate, and the anionic alkyl chain length were studied. All systems showed substantial negative deviations (lower CMC) from ideal solution theory. The results can be represented by regular solution theory. Charge separation appears to be the source of the nonideality. This considers the reduction of electrostatic repulsion between the ionic surfactant head groups in the mixed micelle, due to the insertion of nonionic hydrophilic groups between these charged groups, to be the cause of enhanced micelle formation. The physical basis of regular solution theory was shown to be consistent with the charge separation effect.

Prediction of the critical micelle concentration of mixtures of alkyltrimethylammonium salts

The validity of Shinoda's equation for the critical micelle concentration (CMC) of a multicomponent soap mixture (1), ∑ C 1+K g m i μ i ′ exp (m iω/kT) ∑ μ i′ exp(m iω/kT)=C 1+K g mix , has been tested for commercial samples of some long-chain alkyltrimethylammonium bromides. The samples were analyzed by gas-liquid chromatography and CMC's were determined at 25°C by conductivity and surface tension measurements. An average value for K g of 0.65 was obtained from the variation of CMC with total gegenion concentration. Good agreement was found between experimental and theoretical CMC values for mixtures of alklytrimethylammonium bromides containing up to seven components.