Phase and rheological behavior of a gemini cationic surfactant aqueous system

Abstract

The phase behavior of aqueous system of a gemini-type cationic surfactant, N,N 0 -dodecyl-2-hydroxyl-N,N,N 0 ,N 0 -tetramethyl diammonium dichloride (simply written as 12-3(OH)-12(2Cl)), has been investigated by various complementary methods. A micellar solution region, a hexagonal liquid crystal phase region and two transition regions in the phase diagram are confirmed by SAXS and polarizing microscopy. Over the concentration range, 10-40 (wt%) of 12-3(OH)-12(2Cl), the viscoelastic properties of 12-3(OH)-12(2Cl) solutions at different temperatures have been determined using steady state and frequency sweep rheological measurements. The results from the FF-TEM study are in good agreement with the predictions from steady shear and dynamic rheology in which the large difference in the rheological behavior between 12-3(OH)-12(2Cl) and 12-3(OH)-12(2Br) at the same conditions might be mainly attributed to the role of the intermolecular hydrogen bonding which occurred between the hydroxyl substituted spacers and chloride counter ion and crystallization water molecule.

Physicochemical Evaluation of Micellar Solution and Lyotropic Phases Formed by Self-Assembled Aggregates of Morpholinium Geminis

“…69 The hydroxyl group containing quaternary ammonium gemini surfactant 12–3(OH)–12 forms H 1 phases between 41 and 59 wt % and then exists as mixed hydrated surfactant monoclinic crystals along with Lα phase between 60 and 97wt %. 65 In contrast to the quaternary ammonium gemini surfactants, the morpholinium gemini surfactants demonstrate the affinity to specifically exist as H 1 lyotropic liquid crystalline phase up to surfactant concentration as high as 96 wt % (for [C12MOR(6)C12MOR]2Br) and 94 wt % (for [C14MOR(6)C14MOR]2Br). Imidazolium gemini surfactant [C 12 im–4–C 12 im][Br 2 ]·2H 2 O exists as mixed H 1 and hydrated solid above 80 wt % up to 95 wt %, and above this concentration, it simply exists as hydrated/nonhydrated solid.…”

Effect of Additives on Surfactant Micelle Shape Transformation: Rheology and Molecular Dynamics Studies

“…These findings could be proved by the obvious shear thinning behavior of the steady-state shear viscosity above the critical shear rate γ̇ c (at which shear thinning appeared). Shear thinning is a classical behavior observed, in most cases, for mixed micellar solutions of surfactants/additives and is generally attributed to surfactant aggregates, including wormlike micelles, lamellar liquid crystals, or rod-like micelles, being destroyed to form aggregations of small structures or the micelle alignment in the flow direction with increasing shear rate, thus leading to a decrease in the viscosity of the system ,, and formation of a non-Newtonian fluid. Figure shows a distinct power-law behavior, with an exponent close to above and within the range of approximately −0.4 to 1 reported for polymer solutions at different concentrations and molecular weights; , thus, the wormlike micelles appeared similar to “living” polymers.…”

“…At appropriate concentrations and/or upon addition of salts, surfactant molecules can form various self-aggregates in aqueous media, such as rod-like and wormlike micelles, vesicles, and liquid crystals (lamellar, hexagonal, and cubic structure). Among these various microstructures, wormlike micelles have attracted much interest in fundamental research and practical applications over the past several decades. − Wormlike micelles can be formed by individual amphiphilic surfactants, with a certain concentration or by adding additives, such as inorganic salts (NaCl and NaBr), strongly binding organic salts (aromatic compounds), and oppositely charged surfactants to dilute solutions of surfactants. From a practical point of view, the application of a single surfactant or two surfactants is not economical due to the high cost of their mass production and purification.…”

Synthesis and characterization of geminis and implications of their micellar solution on ninhydrin and metal amino acid complex

“…Being dependent on alkyl head group, hydrophobic chain and length of spacer as well as structures of consisting species, studies of gemini surfactants and their aggregates provide several valuable applications in the field of surface and interfacial sciences [26][27][28][29][30]. Most of the current reports available are also focused on the micellar and surface-active properties of gemini surfactants [31][32][33][34].…”