Thermally induced structural transitions from fluids to hydrogels with pH-switchable anionic wormlike micelles

[Display omitted] ► A pH-switchable anionic wormlike micellar system based only on natural renewable erucic acid has been developed. ► The system can be easily prepared by adding NaOH and is responsive in alkaline conditions. ► Thermally induced transitions from fluid-like solutions to solid-like hy...

Full description

Saved in:
Bibliographic Details
Published in:Journal of colloid and interface science 2013-03, Vol.394, p.319-328
Main Authors: Zhang, Yongmin, Han, Yixiu, Chu, Zonglin, He, Shuai, Zhang, Jichao, Feng, Yujun
Format: Article
Language:English
Subjects:
anionic surfactants
Chemistry
Colloidal gels. Colloidal sols
Colloidal state and disperse state
crystallization
Erucic acid
Exact sciences and technology
Fluid dynamics
Fluid flow
Fluids
gels
General and physical chemistry
hydrocolloids
Hydrogels
hydrophobicity
Micelles
Micelles. Thin films
pH-switchable
rheology
Sodium
Surfactant hydrogels
temperature
transmittance
Ultra-long-chain anionic surfactant
viscoelasticity
Viscosity
Wormlike micelles
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:[Display omitted] ► A pH-switchable anionic wormlike micellar system based only on natural renewable erucic acid has been developed. ► The system can be easily prepared by adding NaOH and is responsive in alkaline conditions. ► Thermally induced transitions from fluid-like solutions to solid-like hydrogels have been investigated. ► Thermally induced structural transitions from fluids to hydrogels with pH-switchable anionic wormlike micelles. A novel pH-switchable anionic wormlike micellar system has been developed by simply changing pH value of natural erucic acid solutions without needing specialized organic synthesis or addition of hydrotropes. Through rheology, optical transmittance, and cryo-TEM observation, it was found that at 60°C, the 100mM erucic acid solutions transform from low viscous emulsion-like fluids to viscoelastic hydrogels when the pH is increased from 8.03 to 12.35, and when the pH is cycled between 9.02 and 12.35, the viscosity of the solutions varies correspondingly between 2 and 200,000mPas, five orders of magnitude in viscosity range. Such a reversible switch can be easily cycled more than four times without any deterioration. In addition, when the pH is fixed between 9.0 and 12.35, the solutions shift to highly elastic solid-like gels with decreasing temperature. These pH-switchable and temperature-sensitive rheological properties are attributed to the presence of carboxylic groups in the erucic acid molecules. With increasing pH, erucic acid is converted into an anionic surfactant, sodium erucate, which self-assembles into aggregates evolving from spherical micelles to wormlike micelles; when temperature is decreased, these disordered micellar structures become highly ordered under the effect of crystallization of hydrophobic erucate chains, forming opaque solid-like hydrogels.
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2012.11.032