Redox and CO2/N2 dual-stimuli responsive wormlike micelles based on ferrocene-carboxylic acid and conventional surfactants

Smart wormlike micelles (WLMs) that respond to environmental stimuli and display tunable rheological properties have attracted considerable interest. However, the responsive surfactants in the smart WLMs are always commercially unavailable. Herein, we report the preparation of CO2/N-2 and redox dual-stimuli responsive wormlike micelles (WLMs) using sodium ferrocenecarboxylic acid (FA), hexadecyl trimethyl ammonium bromide (CTAB), and N,N-dimethylhexadecylamine (CDA), which are all commercially available compounds. The ferrocene group in FA can be reversibly switched between its oxidized and reduced forms by redox reactions, which would alter the hydrophilic properties of FA. Consequently, by alternately adding H2O2 and NaBH4, WLMs can be reversibly destoryed and reformed because of the redox-responsiveness of FA. Moreover, WLMs can also be switched on and off by cyclically bubbling CO2 and N2, resulting from the reversible protonation of CDA. The multi-stimuli responsive WLMs (CTAB-FA-CDA) may have potential applications in oil recovery and fluid drag reducers.