Interactions in the mixed micelles of monomeric and gemini surfactants: Influence of some co-solvents as a function of temperature

AbstractMixed micellar behavior of a series of m-2-m cationic gemini surfactants (where m=10, 12 and 14) with monomeric surfactants (dodecyltrimethylammonium bromide, tetradecyltrimethyl-ammonium bromide and cetyltrimethylammonium bromide) has been studied in aqueous and in aqueous n-propanol, n-butanol, tertiary butanol, propylene glycol and glycerol solutions using conductivity, surface tension, viscosity and dynamic light scattering techniques at 298.15, 308.15 and 318.15K, respectively. In mixtures of 10–2–10 with monomeric surfactants, the synergistic interactions increase with the chain length of monomeric surfactants whereas the mixtures with 12–2–12 and 14–2–14 exhibit the opposite trends. However, the synergistic interactions decrease with the increase in temperature of all the mixtures. The thermodynamic and surface parameters have been evaluated and the influence of the variations in hydrophobic chain length of the surfactants and the type of the co-solvent on these parameters has been discussed. The hydrodynamic diameter increases with the chain length of the surfactants

Volumetric and Viscometric Studies on Saccharide-Disodium Tetraborate (Borax) Interactions in Aqueous Solutions

The densities, ρ, and viscosities, η, of some mono-, di-, and trisaccharides in (0.05, 0.10, 0.12, and 0.15) mol·kg^–1 aqueous disodium tetraborate (borax) solutions have been determined at (288.15 to 318.15) K, by using a vibrating-tube digital densimeter and an Ubbelohde-type capillary viscometer, respectively. From these data, the standard partial molar volumes at infinite dilution, <i>V</i>₂° and Jones-Dole viscosity <i>B</i> coefficients have also been evaluated. Their significantly large positive values vary with the size of saccharides, i.e., from mono- to di- to trisaccharides. The results have been discussed in terms of the solute–cosolute interactions occurring in these solutions

Interactions between Sulpha Drugs and Magnesium Chloride in Aqueous Solutions at <i>T</i> = (288.15 to 318.15) K: Volumetric and Viscometric Approach

The densities (ρ) and viscosities (η) for sulphanilamide, sulphanilic acid, and sulphosalicylic acid dihydrate in aqueous solutions of magnesium chloride hexahydrate (0.05, 0.1, 0.25, and 0.5) mol·kg^–1 at temperatures from (288.15 to 318.15) K have been measured by using vibrating tube digital densimeter and Micro–Ubbelohde type capillary viscometer, respectively. These data have been used to obtain partial molar volumes (<i>V</i>₂⁰) at infinite dilution and viscosity <i>B</i> coefficients. The present partial molar volumes and <i>B</i>-coefficient data in conjunction with that reported in water have further been used to calculate the corresponding transfer parameters (Δ_tr<i>V</i>₂⁰ and Δ_tr<i>B</i>). The results have been compared with the data already reported for these drugs in aqueous sodium chloride solutions

Volumetric Properties of Disaccharides in Aqueous Solutions of Benzyldimethylammonium Acetate as a Function of Temperature

Densities, ρ, and speeds of sound, <i>u</i>, of two disaccharides (D-(+)-maltose and D-(+)-cellobiose) in water and in the presence of protic ionic liquid (PIL) (i.e., benzyldimethylammonium acetate, BDMAAc) were measured at different temperatures (288.15–318.15) K at atmospheric pressure. These data were used to calculate the apparent molar volume, apparent molar isentropic compressibility, infinite dilution partial molar volume, infinite dilution partial molar isentropic compressibility, and corresponding transfer parameters (Δ_t<i>V</i>°₂ and Δ_t<i>K</i>°_s,2) for disaccharides from water to aqueous PIL solutions. The effect of BDMAAc on the basic taste quality of disaccharides was evaluated from apparent specific volume and apparent specific isentropic compressibility, as these parameters are grouped in various taste qualities

Lamellar phase supported synthesis of colloidal gold nanoparticles, nanoclusters, and nanowires

Gold nanoparticles (Au NP) have been synthesized in aqueous phase under ambient conditions in the presence of a series of various cationic double chain as well as dimeric (gemini) surfactants. The spacer chain and twin tail length of these surfactants has been systematically varied to see the effect of hydrophobicity on their capping ability. It has been observed that the increase in the length of spacer chain (from 12-2-12 to 12-6-12) and twin tails (from 10-2-10 to 14-2-14) significantly increases the lamellar phase formation and which in return acts as a wonderful template to accommodate the NP in the form of nanoclusters and nanowires. The lamellar phase practically facilitates the nucleation of Au\ub0 and produces large NP (15\ub12 nm). All reactions have also been carried out in the presence of \ue701-cyclodextrin (CYC) which has strong ability to complex with surfactant tail. The presence of CYC induces a tendency to form nanowire and it is more prominent in the case of surfactants with longer spacer group.Peer reviewed: YesNRC publication: Ye

Novel Biodegradable Films with Extraordinary Tensile Strength and Flexibility Provided by Nanoparticles

A simple method has been proposed to synthesize environmental friendly biodegradable starch films containing gold (Au) and cadmium sulfide (CdS) nanoparticles (NPs) with significantly improved mechanical properties than pure starch films for various industrial applications. Au NPs were synthesized in vitro by using starch as a weak reducing agent simultaneously for the starch film formation. All reactions were monitored with UV–visible measurements, and it was observed that the growth of Au NPs was proportional to the amount of starch. Due to the inherent surface plasmon resonance (SPR), all Au NP starch films were UV active. Likewise, CdS NPs were synthesized in the glycerol medium and further incorporated in the starch films to make fluorescent active films. X-ray diffraction (XRD), transmission electron microscopy (TEM), atomic force microscopy (AFM), and differential scanning calorimetry (DSC) measurements were used to characterize NPs as well as starch films. A systematic measurement of mechanical properties showed a high degree of tensile strength and flexibility for CdS fluorescent starch films in comparison to Au NP starch films that made the former an ideal candidate for various industrial applications