Preparation and Insights of Smart Foams with Phototunable Foamability Based on Azobenzene-Containing Surfactants

Abstract

Smart foams with tunable foamability exhibit superb applications in many fields such as colloidal and interface science. Herein, we have synthesized an azobenzene-containing surfactant with excellent photoresponsiveness by a simple thiol-maleimide click reaction between thioglycolic acid and 4-(N-maleimide) azobenzene (MAB). The structure and the photoresponsive behavior of the novel surfactant are characterized. Depending on the solution concentration, the synthesized surfactant demonstrated various speeds for the trans/cis photoisomerization varying from 9 to 24 s for the given concentration range and excellent reversible photoisomerization cycling stability (more than 20 cycles) upon light irradiation. Based on these conformational switches, a series of phototriggered obvious surface properties (e.g., critical micelle concentration (CMC), surface tension (γ), and surface excess concentration (Γ)) changes of the surfactant are achieved. More specifically, the smart foam system with tunable foamability is realized. As-formed smart foams with rapid photocontrolled reversible foaming/defoaming transition and excellent cycling stability make them very attractive candidates for applications in wastewater treatment, green textile, oil extraction, and emulsification.

Robust Scalable-Manufactured Smart Fabric Surfaces Based on Azobenzene-Containing Maleimide Copolymers for Rewritable Information Storage and Hydrogen Fluoride Visual Sensor

“…As shown in Figure 1B, the feature peaks at 7.00, 7.54, and 7.99 ppm belong to the −CH− of the phenyl group in MAB (m, 1H). 48 The multiple The carbonyl peaks of TFEMA and MAB in copolymers can be seen at 1741, 1749, and 1716 cm −1 . 46,48 The characteristic absorption peaks of the −CF 3 group are observed at 1109 to 1161 cm −1 .…”

“…Monomer 4-(N-maleimide)azobenzene (MAB) was synthesized according to the previous work. 48 All of the reagents were directly used except special explanation.…”

Consideration of Azobenzene-Based Self-Assembled Monolayer Deposition Conditions for Maximizing Optoelectronic Switching Performances

“…The FAZO concentration in all the solutions was fixed at 10 μM, which is ∼100 times lower than the critical micellar concentration of azobenzene-based surfactants. Consequently, severe aggregation and micelle formation would be negligible during the SAM formation process . The SAM formation process can be divided into rapid absorption and crystallization (or ordering) steps.…”

“…Consequently, severe aggregation and micelle formation would be negligible during the SAM formation process. 26 The SAM formation process can be divided into rapid absorption and crystallization (or ordering) steps. The interaction between the solvent and thiol derivative can vary depending on the magnitude of the dipole moment and/or the polarity of the solvent used to dissolve the solute.…”

Bioinspired Photo-Responsive Liquid Gating Membrane

“…Inspired by the fluid transport and switchable properties of stomata [ 6 ], we have constructed a bioinspired photo-responsive liquid gating membrane (BPRLGM), which can be reversibly switched between closed and open states under alternating UV and visible light irradiations. To realize the photo-responsibility of the liquid gating membrane, we synthesized azobenzene-based photo-responsive surfactant molecules (AzoC 8 F 15 ) by a facile one-step substitution method [ 23 , 24 ]. Then, the AzoC 8 F 15 molecules were dissolved in N,N-Dimethylacetamide (DMAC) to form the photo-responsive gating liquid.…”