Hexa-ethyleneglycol Mono N-dodecyl Ether Research Articles

Peculiarities of linear and hyperbranched polyglycidols in water and aqueous surfactant solutions

Linear and hyperbranched polyglycidol (LPGL and HPGL) with average molecular weight of a few thousands were studied in water and surfactant solutions. The employed surfactants are hexaethyleneglycol mono n-dodecyl ether (C12E6), cetyl trimethyl ammonium bromide (CTAB) and sodium dodecyl sulfate (SDS). The working methods are surface tension, steady-state fluorescence, dynamic light scattering (DLS), electrokinetic potential and FTIR spectroscopy. The linear polyglycidols are weakly associative species, unlike the hyperbranched one which is more hydrophilic and harder associates. The linear polymers most efficiently interact with the anionic surfactant, followed by cationic and most weakly with the nonionic. The hydrodynamic diameters of the investigated polyglycidols depend on their structure and molecular weight. In the presence of SDS, the hydrodynamic diameters vary with surfactant concentration. The study reveals the solubilization of fluorescent probes (pyrene, naphthalene) inside the polyglycidol aggregates. Unlike the LPGL, the presence of cavities in HPGL macromolecule offers supplementary “pockets” for solubilization.

Spectroscopical properties of a DTAF-labeled hydrophilic–hydrophobic copolymer in water and surfactant micelles

Emulsion copolymerization of hydrophilic α-tert-butoxy-ω-vinylbenzyl-polyglycidol macromonomer with styrene yields core–shell microspheres and a water-soluble copolymer fraction. This copolymer has a higher content of hydrophilic polyglycidol attested by 1H NMR. Further information is acquired by labeling the copolymer with 5-(4,6-dichlorotriazinyl)aminofluorescein (DTAF) and making absorption and fluorescence studies. The acquired data on aqueous solution of labeled copolymer without (L) and with micelles of dodecyltrimethylammonium chloride (LD), sodium dodecylsulfate (LS) and hexaethyleneglycol mono n-dodecyl ether (LE) reveal that the dianionic and anionic tautomers of the DTAF-label are apparent and concordant with the recorded spectrophotometric pKa values. The emission intensities, quantum yields and lifetimes obey the sequence LE < LS < L < LD. They are along with the increasingly deprotonated forms of the fluorophore and unveil that the micelle-label interactions depend on the surfactant.

Friction force measurements relevant to de-inking by means of atomic force microscope

In the pulping step of the de-inking process, the ink detaches from the fibers due to shear and physical chemical interaction. In order to get a better understanding of the forces involved between cellulose and ink, the atomic force microscope and the colloidal probe technique have been used in the presence of a model chemical dispersant (hexa-ethyleneglycol mono n-dodecyl ether, C12E6). A cellulose bead was used as the colloidal probe and three different lower surfaces have been used, an alkyd resin, mica and a cellulose sphere. The normal and lateral forces have been measured at a range of nonionic concentrations. It was found that the lateral sliding friction forces deceased with increasing surfactant concentration for both the alkyd resin and mica while no differences were observed for the cellulose surface. In addition, only a very small change in normal force could be detected for the alkyd surface as the concentration changed.

Are Aqueous Sodium Dodecyl Sulfate Micelles in the Presence of Added Salt Polydisperse? A Time-Resolved Fluorescence Quenching Study with Global Analysis

Aggregation numbers of aqueous sodium dodecyl sulfate (SDS) in the presence of added salt were estimated using the time-resolved fluorescence quenching method. Tris (2,2‘-bipyridyl)ruthenium(II) and 1-ethylpyrene were used as probes and 9-methylanthracene, 3,4-dimethylbenzophenone, and 1-dodecylpyridinium chloride were used as quenchers. It was found that aqueous SDS micelles are monodisperse even in the presence of high salt concentrations contrary to what has been reported. Similar studies were carried out using the nonionic surfactant hexaethylene glycol mono-n-dodecyl ether (HEGDE) in water. Aqueous 33.1% (w/w) HEGDE solutions were found to be polydisperse.

An Apparatus for the Study of Surface Longitudinal Waves at the Air/Water Interface

An apparatus used to study air/water interfacial surface viscoelasticity through longitudinal waves is described. The longitudinal surface waves are generated by an oscillating barrier driven by a small DC motor and detected with a capillary wave. The damping coefficient and the wavenumber of the longitudinal wave are measured simultaneously by using a "double lock-in" technique. Experimental results of interfacial viscoelasticity for C12E6 (hexaethyleneglycol mono n-dodecyl ether) are reported.

Precipitation of surfactant salts: II. The effect of nonionic surfactants on precipitation of calcium dodecyl sulfate

The effects of two nonionic surfactants (hexaethyleneglycol mono n-dodecyl ether, C 12E 6, and octaethylegneglycol dodecyl ether, C 12E 8) on the precipitation of calcium dodecyl sulfate, Ca(DS) 2, have been studied as a function of the concentration of all reacting components. The addition of C 12E 6 and C 12E 8 greatly enhances the solubility of Ca(DS) 2. The results are explained in terms of mixed micelle formation based on the regular solution theory taking into consideration the counterion exchange at micelles.

Displacement disorder in a liquid crystalline phase with cubic symmetry

The cubic phase of the lyotropic system hexa-ethyleneglycol mono n-dodecyl ether (C 12 EO 6 )/water is studied by small angle X-ray scattering, at the synchrotron radiation facility of LURE. The indexation of 15 Bragg reflections is strongly in favor of a body-centred cubic structure with space group Ia3d. The presence of diffuse scatterings in reciprocal space demonstrates the existence of large fluctuations of position in the crystal. The organization of these diffuse scatterings indicates that these fluctuations correspond to a linear disorder caused by displacements along directions. These displacements are discussed within the framework of the structural model usually proposed for Ia3d cubic phases. Their existence can be understood considering the usual mechanical properties of liquid crystals Etude par diffusion des rayons X aux petits angles de la phase cubique du systeme lyotrope mono n-dodecyl ether hexa-ethyleneglycol (C 12 EO 6 )/eau. Proposition d'une structure cubique centree dont le groupe d'espace est Ia3d. Existence d'importantes fluctuations de position dans le cristal, correspondant a un desordre lineaire du a des deplacements le long des directions

Interaction of surfactants with vesicle membrane of dipalmitoylphosphatidylcholine. Effect on gel-to-liquid-crystalline phase transition of lipid bilayer

The gel-to-liquid-crystalline phase transition of dipalmitoylphosphatidylcholine (DPPC) vesicle membrane was observed in the presence of various types of surfactants: sodium alkylsulfates, alkyltrimethylammonium bromides, alkanoyl- N-methylglucamides, and hexaethyleneglycol mono n-dodecyl ether. The phase transition was monitored by a change in scattered light intensity of the lipid suspension. For all the surfactants examined, the phase transition temperature was depressed linearly with the surfactant concentration in the measured concentration range, from which the partition coefficient, K, of the surfactant between bulk solution and lipid membrane was estimated. Except alkyltrimethylammonium bromides, log K and log CMC showed a linear relationship, which indicates that the driving force to transfer the surfactant from bulk solution to lipid membrane is a hydrophobic interaction. The addition of surfactants increased the transition width. The extent of widening the transitionwidth was in the order of sodium alkylsulfate > alkyltrimethylammonium bromides > hexaethyleneglycol mono n-dodecyl ether; in the case of alkanoyl- N-methylglucamides, the transition width was not affected by the addition. These effects on the transition width was interpreted qualitatively in terms of the cooperativity of the transition.