Synergistic Rheological Behavior of Mixed Micellar Solutions of Surfactin and Cetyl Trimethyl Ammonium Bromide

Abstract

This paper investigated the rheological properties of novel viscoelastic thickening micelle system formed by surfactin and cetyl trimethyl ammonium bromide (CTAB). The total concentration of surfactin and CTAB was maintained at 12 wt%. The rheological behavior of the surfactin/CTAB synergistic micelles with different mass ratio and pH was systematically investigated. For the surfactin/CTAB micellar system with a mass ratio varied from 1/11 to 4/8, the viscosity of the micelles rose to a maximum with increasing pH, and then decreased with a further increase of pH. When the mass ratio was surfactin: CTAB = 2.5:9.5 (pH 5.72), the maximum viscosity of the micelle solution reached 8170 mPa. s. Meanwhile, the viscosity curve of the surfactin/CTAB systems was described by the nonlinear co-rotational Jeffreys model. This work sets a rheological foundation for the application of surfactin/CTAB systems. The thixotropic loop area of the micelles was basically zero. Through viscoelasticity measurements, the results demonstrated that the appropriate surfactin/CTAB mass ratio would favor the stability of the network structure of the synergistic thickening system. The value of G 00 (viscous modulus) is always higher than the value of G 0 (elastic modulus).

Viscoelastic micellar system of mixed surfactin and octadecyl trimethyl ammonium chloride

“…The results showed that the strength of internal structures could be controlled and improved by adjusting the mass ratio of the surfactin/OTAC system. Compared with the surfactin/ CTAB system studied by Zhao (Zhao et al, 2020), the surfactin/OTAC viscoelastic system had more obvious thixotropic loops and more complex micelle structures.…”

“…When the ratio of OTAC was larger and the pH of the solution was controlled between 5.20 and 5.40, the system had a more significant synergistic thickening effect. Zhao et al (2020) obtained the surfactin/CTAB viscoelastic micelle system at the optimal mass ratio of 2.5/9.5 and the optimal pH condition of 5.27 to reach the maximum viscosity of 8170 mPa s (25 C, shear rate 10 s À1 ). The maximum viscosity of the surfactin/OTAC system was 1.7 times that of the surfactin/CTAB system, which greatly improved the viscosity of the surfactin surfactant compound system.…”

“…Halogenated cationic surfactants are widely used in daily chemical products. Zhao studied the synergistic thickening composite system of surfactin and cationic surfactant CTAB (Zhao et al, 2020). However, CTAB is limited in the application due to the presence of bromine ions.…”

Evaluation of mixed micellar interactions of CnBCl and SDBS mixtures using dissociated Margules model and influence of different salts

“…From the industrial and academic point of view, the properties of mixed surfactant systems are more significant than those of single surfactant. The mixtures of cationic and anionic surfactants exhibit relatively more synergistic effect among various binary mixtures of surfactants due to strong attractive interaction between the head‐groups with opposite charges (Holland & Rubingh, 1992; Lao et al, 2018; Mehbub et al, 2019; Miraglia et al, 2011; Moallemi et al, 2011; Wang & Yang, 2021; Wei et al, 2021; Zhao et al, 2020). However, bulk of the studies has been focused on the evaluation of parameters based upon CMC 1 of the mixtures whereas the reports on the involvement of CMC 2 are scarce (Miraglia et al, 2011; Talhout & Engberts, 1997; Zana et al, 1997).…”