Key Laboratory of Synthetic and Biological Colloids, Ministry of Education, School of Chemical & Materials Engineering, Jiangnan University , Wuxi, Jiangsu 214122, China.
Fujian Provincial Key Laboratory of Featured Materials in Biochemical Industry and Fujian Province University Key Laboratory of Green Energy and Environment Catalysis, Ningde Normal University , Ningde, Fujian 352100, China.
Langmuir. 2017 Aug 15;33(32):7908-7916. doi: 10.1021/acs.langmuir.7b00934. Epub 2017 Aug 3.
Innovation in the structure of surfactants is crucial to the construction of a surfactant-based system with intriguing properties. With dehydroabietic acid as a starting material, a nearly totally rigid azobenzene surfactant (R-azo-Na) was synthesized. The trans-R-azo-Na formed stable foams with half-lives of 636, 656, 976, and 872 min for 0.3, 1, 2, and 4 mmol·L aqueous solutions, respectively. Under UV light irradiation, a fast collapse of the foams was observed, showing an in situ response. The excellent foam stability of trans-R-azo-Na leads to the extremely high photoresponsive efficiency. As revealed by dynamic surface tension and pulsed-field gradient NMR methods, an obvious energy barrier existed in the adsorption/desorption process of trans-R-azo-Na on the air/water interface. The foams formed by trans-R-azo-Na are thus stable against coarsening processes. The results reveal the unique photoresponsive behavior of a surfactant with a rigid hydrophobic skeleton and provide new insights into the structure causing aggregation of surfactants.
创新表面活性剂的结构对于构建具有有趣性质的基于表面活性剂的系统至关重要。以脱氢枞酸为起始原料，合成了一种几乎完全刚性的偶氮苯表面活性剂（R-偶氮-Na）。形成的反式-R-偶氮-Na 在 0.3、1、2 和 4 mmol·L 水溶液中分别具有半衰期为 636、656、976 和 872 min 的稳定泡沫。在紫外光照射下，观察到泡沫快速坍塌，表现出原位响应。反式-R-偶氮-Na 具有优异的泡沫稳定性，导致其具有极高的光响应效率。通过动态表面张力和脉冲梯度核磁共振方法揭示，反式-R-偶氮-Na 在气/水界面上的吸附/解吸过程中存在明显的能量障碍。因此，由反式-R-偶氮-Na 形成的泡沫不易粗化。这些结果揭示了具有刚性疏水性骨架的表面活性剂的独特光响应行为，并为导致表面活性剂聚集的结构提供了新的见解。
