Synergistic Behavior and Microstructure Transition in Mixture of Zwitterionic Surfactant, Anionic Surfactant, and Salts in Sorbitol/H₂O Solvent: 1. Effect of Surfactant Compositions

Abstract

The phase behavior and rheological properties of a multi‐component system, made of a zwitterionic surfactant cocoamidopropyl betaine (CAPB), an anionic surfactant sodium lauryl sulfate (SLSS), and mixed salts (tetrasodium pyrophosphate, sodium acid pyrophosphate, sacharrin, and sodium fluoride) in sorbitol/H2O mixed solvent at different mass fraction of SLSS (XSLSS) were systematically investigated by steady and dynamic rheology, dynamic light scattering, and diffusion ordered spectroscopy (DOSY). When fixing the salt concentration and the mass ratio of sorbitol in mixed solvent (R), the zero‐shear viscosity increases first and then decreases showing a maximum with increasing XSLSS, resulting from the formation and entanglement of wormlike micelles. Especially when XSLSS is between 0.33 and 0.80, the mixture is dominated by entangled wormlike micelles coexisting with small micelles and separated wormlike micelles, and shows high viscoelasticity. The maximum of the zero‐shear viscosity is ca. 5 orders of magnitude larger than that of sorbitol/H2O mixed solvent or the CAPB/SLSS aqueous solution. The characteristic structural parameters for the micellar solutions at different XSLSS are also estimated from further analysis of the rheological results, and indicate the stronger network structures of the wormlike micelles are formed in our systems compared with the wormlike micelles formed by a traditional zwitterionic/anionic surfactant aqueous solutions. The great improvements of rheological properties are attributed to the strong screening effects of the mixed salts and the strong solvophobic effect of sorbitol on the electrostatic and hydrophobic interaction between the CAPB and SLSS molecules. The present work has improved our understanding about the aggregation behavior of zwitterionic/anionic mixed surfactants with salts in less polar solvent/H2O mixture, which would be of widely practical importance to optimize the formulation of products for personal care and household cleaning.

Rheological Properties and Microstructure Transition in Mixture of Zwitterionic Surfactant, Anionic Surfactant and Salts in Sorbitol/H2O Solvent: 2. Effect of Salts and Sorbitol

“…Regardless of the R value, the zero steady-shear viscosity follows the same trends as the concentration curve with increasing SLSS content. Similar to studies [34,35], the system changes from a Newtonian fluid to a non-Newtonian fluid and then back to Newtonian fluid with increasing X SLSS , indicating the transition from separated wormlike micelle to entangled wormlike micelle coexisting with small micelles over the entire transition process. In order to study the effects of sorbitol on the rheological properties of the multi-component system, the viscosity of the mixed system in salts/H 2 O without sorbitol was also included as a comparison and we found that the viscosity can approach 100 Pa s at the optimal X SLSS attributed to the electrostatic screening effect of mixed salts.…”

Synergistic Influence of pH and Temperature on Rheological Behavior of Adhesive Emulsions Stabilized with Micelle Dispersion of an Anionic Surfactant

“…This is an indication of a liquid–solid (sol–gel) transition due to electrostatic repulsions, which enhances the stability of the emulsion and may even form a weak crystalline solid (Mewis and Wagner, ). These shear‐induced phenomena also termed as Shear banding (SB) that was observed in a variety of other complex fluids, such as lamellar surfactant phases (Fan et al, ; Salmon et al, ), wormlike micelles (Mei et al, ; Wei et al, ), suspensions (Ragouilliaux et al, ), and polymeric solutions (Kamal et al, ; Ravindranath et al, ). The SB phenomenon is the stratification of the flow into regions of high and low shear rates, , connected by an “interface” of sharp change in which this homogeneous velocity gradient profile becomes unstable to heterogeneous perturbations and splits into high and low shear rate bands that coexist in the cell, so that the local shear rate varies spatially .…”

Prediction of Aqueous Solution Surface Tension of Some Surfactant Mixtures and Composition of Their Monolayers at the Solution—Air Interface

“…The reduction magnitude depends on the kind of surfactants and/or surfactant mixtures and their concentration in the aqueous solution. In the case of surfactant mixtures, the magnitude of the water surface tension reduction by the mixed monolayer formed at the water-air interface also depends on the composition of the mixture in the bulk phase [7][8][9][10].…”