Butler Calum S G, Giles Luke W, Sokolova Anna V, de Campo Liliana, Tabor Rico F, Tuck Kellie L
School of Chemistry, Monash University, Clayton, Victoria 3800, Australia.
Australian Centre for Neutron Scattering, ANSTO, Lucas Heights, New South Wales 2234, Australia.
Langmuir. 2022 Jun 21;38(24):7522-7534. doi: 10.1021/acs.langmuir.2c00523. Epub 2022 Jun 9.
Azobenzene-containing surfactants (azo-surfactants) have garnered significant attention for their use in generating photoresponsive foams, interfaces, and colloidal systems. The photoresponsive behavior of azo-surfactants is driven by the conformational and electronic changes that occur when the azobenzene chromophore undergoes light-induced ⇌ isomerization. Effective design of surfactants and targeting of their properties requires a robust understanding of how the azobenzene functionality interacts with surfactant structure and influences overall surfactant behavior. Herein, a library of tail substituted azo-surfactants were synthesized and studied to better understand how surfactant structure can be tailored to exploit the azobenzene photoswitch. This work shows that tail group structure (length and branching) has a profound influence on the critical micelle concentration of azo-surfactants and their properties once adsorbed to an air-water interface. Neutron scattering studies revealed the unique role that intermolecular π-π azobenzene interactions have on the self-assembly of azo-surfactants, and how the influence of these interactions can be tuned using tail group structure to target specific aqueous aggregate morphologies.
含偶氮苯的表面活性剂（偶氮表面活性剂）因其在生成光响应性泡沫、界面和胶体体系中的应用而备受关注。偶氮表面活性剂的光响应行为是由偶氮苯发色团发生光致⇌异构化时所发生的构象和电子变化驱动的。要有效地设计表面活性剂并针对其性质进行调整，就需要深入了解偶氮苯官能团如何与表面活性剂结构相互作用以及如何影响表面活性剂的整体行为。在此，合成并研究了一系列尾部取代的偶氮表面活性剂库，以更好地理解如何通过调整表面活性剂结构来利用偶氮苯光开关。这项工作表明，尾部基团结构（长度和支化度）对偶氮表面活性剂的临界胶束浓度以及它们吸附到气-水界面后的性质有着深远影响。中子散射研究揭示了分子间π-π偶氮苯相互作用在偶氮表面活性剂自组装过程中所起的独特作用，以及如何利用尾部基团结构来调节这些相互作用的影响，从而实现特定的水性聚集体形态。
