A facile route to design pH-responsive viscoelastic wormlike micelles: Smart use of hydrotropes.
A simple and effective route to design pH-responsive viscoelastic wormlike micelles based on commercial compounds is reported. According to this route, pH-sensitive viscoelastic fluids can be easily obtained by introducing a pH-responsive hydrotrope into a surfactant solution. In this paper, the mixed system of cetyltrimethylammonium bromide (CTAB) and potassium phthalic acid (PPA) was studied in detail. This pH-sensitive fluid can be switched between a gellike state and a waterlike state within a narrow pH change. Rheology and DLS results revealed that the pH-sensitive flowing behavior was attributed to the microstructure transition between wormlike micelles and short cylindrical micelles. Combined with fluorescence anisotropy, NMR, and UV-vis, it was demonstrated that the pH response of viscoelastic fluid originated from the different binding abilities of hydrotrope to surfactant as pH varies. Furthermore, different kinds of hydrotropes can be utilized to prepare pH-responsive viscoelastic fluids in the desired pH areas.
Lin
Yiyang
Y
Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, People's Republic of China.
Han
Xue
X
Huang
Jianbin
J
Fu
Honglan
H
Yu
Cailan
C
D000077286:Cetrimonium; D002593:Cetrimonium Compounds / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008823:Micelles; D008968:Molecular Conformation; D044367:Phase Transition; D010795:Phthalic Acids / Q000737:chemistry*; D012212:Rheology
D002593:Cetrimonium Compounds; D008823:Micelles; D010795:Phthalic Acids; C032279:phthalic acid; D000077286:Cetrimonium