生物基表面活性剂七叶皂素的界面行为

以天然三萜皂苷七叶皂素为研究对象, 分别采用吊片法、 悬滴法和高速摄像机动态拍摄法探究了七叶皂素分子在气-液、 液-液、 固-液界面的界面行为. 考察了以七叶皂素为乳化剂制备乳液的性质, 以及七叶皂素对液滴在疏水固体表面润湿铺展行为的调控规律, 并从分子层次角度分析了作用机理. 结果表明, 七叶皂素能在气-液界面发生吸附, 将水的表面张力降低至42.1 mN/m, 临界胶束浓度为5×10^?4 mol/L. 七叶皂素还可以在油-水界面吸附, 将亲油端插入油相, 亲水端插入水相, 形成稳定的界面膜, 降低界面张力. 以七叶皂素为乳化剂所制备的乳液, 随着浓度增大可以达到较小的粒径和较大的Zeta电势, 短时间内表现出较好的稳定性. 高浓度的七叶皂素可以很好地抑制液滴在疏水固体表面的弹跳和回缩, 达到很好的铺展效果, 有利于拓展其在诸多领域的应用.

Interfacial Behaviors of Bio-based Surfactant Escin

The interfacial behaviors of natural triterpene saponin escin at gas-liquid， liquid-liquid， and solid-liquid interfaces were investigated by Wilhelmy method， pendant drop method， and high-speed camera dynamic shooting method， respectively. The properties of the emulsion prepared with escin as the emulsifier and the regulation of escin on droplet impact behavior on hydrophobic solid surface were investigated， and the mechanism were analyzed from molecular level. The results showed that escin could be adsorbed at the air- water interface， and the surface tension of water was reduced to 42.1 mN/m with the critical micelle concentration of 5×10^?4 mol/L. In addition， escin molecules can also be adsorbed at the oil-water interface， inserting the hydrophobic skeleton into the oil phase and the hydrophilic headgroup into the water phase to form a stable interfacial film， finally reducing the interfacial tension. With the increase of the concentration， the emulsion prepared with escin as the emulsifier could achieve smaller particle size， larger Zeta potential， and showed good stability in a short period of time. Moreover， the bounce and retraction of droplet on hydrophobic solid surface could be obviously inhibited by escin with higher concentration， leading to good spreading， which is conducive to its application in many fields.