Micellar Aggregation Behavior and Electrochemically Reversible Solubilization of a Redox-Active Nonionic Surfactant

Abstract

For the purpose of studying the potential of a novel nonionic switchable surfactant, 11-ferrocenylundecyl polyoxyethylene ether (FPEG), applied to surfactant-enhanced remediation (SER), the surface properties and micelle solubilization behavior of FPEG were investigated with different inorganic salts. With the addition of inorganic salts (NaCl and CaCl 2 ), the critical micelle concentration (CMC) of FPEG dropped from 15 to 12 and 8 mgÁL -1 , respectively, due to the salting-out effect on the alkyl chain. Thermodynamic parameters based on the CMCs indicated that micelle formation was an entropydriven process. Dynamic light scattering measurements verified that these inorganic salts can decrease the hydrodynamic diameters (D h ) of the micelles. Solubilization experiments with three typical polycyclic aromatic hydrocarbons (PAHs) demonstrated that the system of FPEG with NaCl shows the highest solubilization ability, and the molar solubilization ratio and micelle-water partition coefficient (K m ) values follow the order pyrene [ phenanthrene [ acenaphthene. After oxidation, PAHs can be released from the micelles through breaking up of the micelles, and the cumulative release efficiency of pyrene, phenanthrene and acenaphthene are 31.2, 42.8 and 44.6 %; the order of release efficiency is opposite to that of the reduced form for solubilization abilities. All the results suggest that the ferrocene-containing, redox-active surfactant FPEG has the potential to be recycled in SER technology through electrochemistry approaches.

Precision Switching in a Discrete Supramolecular Assembly: Alkali Metal Ion‐Carboxylate Selectivities and the Cationic Hofmeister Effect

“…In contrast, assembly‐state switching of micelles and their ilk – from a population of broad dispersity to a new population of equally wide dispersity – have been more thoroughly explored. Thus, it is well established that charged micelles respond to changes in ionic strength by adjusting their critical micelle concentration, size or aggregation number, or by undergoing structural transitions such as micellar sphere‐to‐rod transitions . Likewise, switchable viscoelastic hydrogels based on bolaamphiphiles that respond to H + , or Na + , and supramolecular polymers/aggregates based on calixarenes that undergo vesicle‐to‐micelle transitions in response to Ag + , have all been reported.…”

Effective and Reversible Switching of Emulsions by an Acid/Base-Mediated Redox Reaction

“…The switchable surfactants can undergo reversible conversions between active and inactive forms under particular stimuli, including light, − pH, − temperature, , CO 2 , ,,− host–guest interactions, magnetism, , and redox reactions. − Generally, emulsions emulsified by switchable surfactants are always switchable under the stimuli. ,,, In most cases, the reversibility of these switchable emulsions has been well-documented. However, from the view point of practical applications, the effectiveness and efficiency of switching processes should not be ignored .…”

Reversibly Redox‐Switchable Anionic Surfactant Contains Two Selenium Atoms

“…Nevertheless, compared with the stimuli by light (Brown et al, ; Takahashi et al, , ), temperature (Feng et al, ; Jia et al, ), magnetism (Brown et al, , ), CO 2 (Brown et al, ; Ceschia et al, ; Jiang et al, ; Liu et al, ; Scott et al, ; Su et al, ; Zhang & Han, ; Zhang, Zhang, et al, ; Zhu et al, ), and electrochemical redox (Aydogan & Abbott, ; Long et al, ; Rosslee & Abbott, ; Saji et al, ; Sakai et al, ; Tsuchiya et al, ), the redox‐switchable process in this work is hindered by some inherent drawbacks, such as the addition of chemicals (H 2 O 2 and Na 2 SO 3 ) and the by‐product Na 2 SO 4 . Although no obvious deterioration of the response of foaming ability, γ , σ , and θ was observed over 5–10 cycles, as demonstrated in Fig.…”

“…Switchable surfactants (Brown, Butts, & Eastoe, ) can undergo reversible conversion between active (ON state) and inactive (OFF state) forms under particular stimuli, including light (Brown et al, ; Takahashi, Fukuyasu, Horiuchi, Kondo, & Stroeve, ; Takahashi, Koizumi, & Kondo, ), pH (Jia, Cheng, Liu, Li, & Dong, ; Lu, Xue, Wang, & Huang, ; Lv, Qiao, & Xiong, ; Yan et al, ; Zhang, An, & Liu, ), temperature (Feng, Verstappen, Kuehne, & Sprakel, ; Jia et al, ), CO 2 (Brown, Wasbrough, Gurkan, & Hatton, ; Ceschia et al, ; Jiang, Zhu, Cui, & Binks, ; Liu, Jessop, Cunningham, Eckert, & Liotta, ; Scott, Robert, Harjani, & Jessop, ; Su et al, ; Zhang & Han, ; Zhang, Zhang, et al, ; Zhu, Jiang, Cui, & Binks, ), host–guest interactions (Wang, Kang, Tang, & Zhang, ), magnetism (Brown et al, , ), and redox reactions (Aydogan & Abbott, ; Fan et al, ; Long, Tian, Li, & Li, ; Rosslee & Abbott, ; Saji, Hoshino, & Aoyagui, ; Sakai, Imamura, Kondo, Yoshino, & Abe, ; Tsuchiya et al, ). Among the aforementioned stimuli, redox reactions are of particular interest because similar processes (oxygen metabolism) occur constantly in living entities (Fuhrmann et al, ).…”

“…Among the aforementioned stimuli, redox reactions are of particular interest because similar processes (oxygen metabolism) occur constantly in living entities (Fuhrmann et al, 2013). Redox-switchable surfactants studied to date have mainly contained ferrocene functional groups (Aydogan & Abbott, 2002;Long et al, 2015;Rosslee & Abbott, 2000;Saji et al, 1985;Sakai et al, 2004;Tsuchiya et al, 2004) or a disulfide bond (Fan et al, 2008). Studies of redoxswitchable surfactants other than those containing ferrocene or disulfide units have rarely been reported.…”