含硒磺基甜菜碱表面活性剂界面性能的氧化-还原响应行为

Redox-Responsive Interfacial Properties of Se-Containing Sulfobetaine Surfactant

硒,作为一种新的氧化-还原响应位点因其良好的生物相容性日益引起人们的关注,然而,对这种新型氧化-还原响应型表面活性剂的研究相对较少,尤其是其界面性能的智能调控。本文以含硒两性离子表面活性剂苄基十一烷基磺基甜菜碱(BSeUSB)为对象,研究了其分子结构、Krafft温度、表/界面张力及发泡和乳化性能的氧化-还原刺激响应行为。发现在极微量的H_2O_2(≤体系总质量的0.056%)氧化下,BSeUSB分子中疏水的―Se―C―键转变成了具有一定亲水能力的Se=O键,表面活性剂从单头单尾的还原态变成了类Bola型的氧化态,导致表面活性剂的Krafft温度由(23.5±0.5)°C下降至0°C以下,5.00 mmol?L^(-1)时的表/界面张力分别从45.15、5.52 mN·m^(-1)升高至61.63、18.38 m N·m^(-1)。宏观上,还原态具有良好的发泡和乳化性能,而氧化态的发泡和乳化能力几乎消失。再次加入极少量还原剂Na_2SO_3(≤体系总质量的0.060%)后,分子的微观结构和溶液性能又可恢复到初始状态。总之,通过极微量H_2O_2和Na_2SO_3的交替加入,我们实现了该表面活性剂界面性能的智能调控。

The use of Se atom as the redox-responsive group has amused considerable attention because of its good biocompatibility. However, only a few efforts have been devoted to Se-containing surfactants, especially for smart control of interfacial properties. This paper focuses on the redox-responsive behaviors, such as molecular structure, Krafft temperature, surface/interfacial tension, foaming, and emulsification of the Se-containing zwitterionic surfactant, 3-（11-benzylselanyl-undecyl）- dimethyl ammonium propane sulfonate （BSeUSB）. After oxidization with a trace of H202 （-〈 0.056% of total mass）, the reduced form BSeUSB with one hydrophilic head and one hydrophobic tail-transformed to the Bola-type oxidized form BSeUSB-Ox due to the presence of a new hydrophilic group （selenoxide）. Therefore, Krafft temperature decreased from （23.5 ± 0.5）℃ to less than 0 ℃. The surface/interfacial tension values at 5.00 mmol.L-1 increased from 45.15, 5.52 mN.m-1 to 61.63, 18.38 mN.m-1, respectively. Macroscopically, BSeUSB has good foaming and emulsification properties, while foaming a emulsification abilities of BSeUSB-Ox were almost non-existent. Interestingly, the initial molecular structure and the solution properties of BSeUSB were regained after reduction with a trace of Na2SO3 （〈 0.060% of total mass）. Thus, by the addition of trace amounts of H2O2 and Na2SO3 alternately, we have achieved smart control of the interfacial properties of the surfactant.