Structure Of Cationic Surfactants Research Articles

Microscopic Evidence for the Correlation of Micellar Structures and Counterion Binding Constant for Flexible Nanoparticle Catalyzed Piperidinolysis of PS− in Colloidal System

Abstract The interest to determine the ionization degree of counterion initiates the need to study the relationship between counterion binding constant (RX Br) and the growth of self-assembly micellar structure. This paper discussed the microscopic evidence for the correlation of counterion binding constant values and micellar structure of cationic surfactants in the presence of phenolates and 2-ethyl phenolates ions in flexible nanoparticle (FN)-system of ionized phenyl salicylate-catalyzed piperidinolysis. The sizes of micelles were determined by particle size analysis. Transmission electron microscopy (TEM) results showed a spherical micellar structure for phenolates and 2-ethyl phenolates ions at counterion binding constant values 6.3 ± 1.0 and 24.0 ± 1.1 respectively. A study using a semi-emperical kinetic technique in published article proved that the suggested micellar structures at respective counterion binding constant values corresponded with the present microscopic evidence.

Cationic surfactants for micellar electrokinetic chromatography: 2. Representative applications to acidic, basic, and hydrophobic analytes

Changes in MEKC chemical selectivity that are induced by changes in the headgroup structure of cationic surfactants are examined. Separations of acidic, basic, and hydrophobic solutes are examined. The acidic analytes are comprised of methoxyphenols, which are of interest due to their prevalence in wood smoke. The basic solutes consist of compounds often found in forensic urine analysis, and represent typical basic pharmaceuticals. The hydrophobic solutes are six pharmaceutical corticosteroids used in replacement therapy of adrenocortical insufficiency and nonspecific treatment of inflammatory and allergic conditions. The role of the headgroup was found to be quite significant when analyzing acidic compounds with not all the surfactants being able to resolve all of the analytes. The headgroup also induced migration order switches among the acidic analytes. All of the surfactants examined here in were found to be suitable for the analysis of basic analytes with each surfactant providing unique selectivity. The hydrophobic solutes were separated best with the larger more hydrophobic surfactant headgroups. The steroid separation with these two surfactants was achieved without the use of organic modifiers or a mixed micellar phase.

Studies on performing chloromethylation reaction for polystyrene by micellar catalysis in aqueous surfactant solutions

This paper puts forward a new method to realize the chloromethylation of polystyrene (PS), and this is the micellar catalysis. The chloromethylation reactions of polystyrene (PS) were carried out in micellar catalysis systems, in which the CCl 4 solution of polystyrene was solubilized in the micelle solutions of surfactants. The mechanism of chloromethylation reaction of polystyrene and the mechanism of the micellar catalysis were explored. The structure of chloromethylated polystyrene (CMPS) was characterized using FT-IR, and its composition was determined with Volhard method. The experimental results show that the micelle solutions of surfactants can solubilize polystyrene dissolved in CCl 4, namely, polystyrene can be transferred into the micelle solutions of surfactants along with solubilization of CCl 4. Micellar catalysis is an effective way to realize chloromethylation for polystyrene. The reaction between polystyrene and formaldehyde and hydrogen chloride consists of electrophilic substitution reaction and nucleophilic substitution reaction. The micellar catalysis of cationic surfactant was more effective than that of anionic surfactant, and this fact displays that the nucleophilic substitution step is a slower reaction step and it is probably the controlling step. Except the types of the surfactants, the structures of cationic surfactants also have effects on the efficiency of the micellar catalysis, and the longer the hydrophobic hydrocarbon chain of cationic surfactant is, the better its catalysis effect is.

Rheological properties and structures of cationic surfactants and fatty alcohol emulsions: effect of surfactant chain length and concentration

Rheological and optical properties of cetyltrimethylammonium chloride (CTAC)/fatty alcohol (FA), behenyltrimethylammonium chloride (BTAC)/FA and CTAC/FA/hydroxyethyl cellulose (HEC) emulsions have been studied with particular emphases on the effects of FA content, the difference in the chain length of the hydrophobic groups between CTAC and BTAC, and the addition of a water soluble polymer, HEC. The effects of the FA content are to accelerate the structure development during the aging period and to increase the storage modulus, the yield stress, and the zero-shear-rate viscosity in the three emulsion systems investigated. At a low FA content of 2% w/w, lamellar and vesicular aggregates and isolated multilamellar vesicles can be observed in the CTAC/FA and BTAC/FA emulsions, respectively. At a high FA content of 6% w/w or with an excess of FA present, networklike structures and sunflower-like structures form, respectively, instead, inducing a higher entanglement storage modulus and a higher yield stress relative to those emulsions with a low FA content. The effect of adding HEC to the CTAC/FA emulsion is to reduce the entanglement storage modulus and the yield stress, consistent with the optical observation that the presence of the polymer disrupts the formations of lamella and vesicular aggregates and network structures.

Effects of Chain Length and Structure of Cationic Surfactants on the Adsorption onto Na–Kaolinite

The adsorption of a series of alkylammonium bromides (RR1N(CH3)2Br) with different chain lengthsRandR1on a nonswelling clay surface (sodium kaolinite) has been studied by microelectrophoresis and adsorption isotherms. An increase in the number of CH2groups in the shorter alkyl chain of the double-chain surfactant, or the introduction of another kind of alkyl group (phenyl group), was found to have much less effect on the adsorption behavior than changing the length of the alkyl chain in the single-chain surfactants. It is inferred that the effective hydrophobicity of the shorter chains in these double-chain surfactants is reduced by their intramolecular association with the longer chain. Comparison of adsorption and micellization leads to an empirical quantitative description of the effects of alkyl chain length and structure on adsorption.