中文摘要：

利用Langmuir膜天平研究了季铵盐三聚表面活性剂12-2-12-2-12在空气-水界面单分子膜的表面压-分子面积（π-A）等温线,得到它的崩溃压对应的表面张力γcollapse和分子极限面积Alimit.与12-2-12-2-12溶液临界胶束浓度对应的表面张力γcmc和由Gibbs吸附方程得到的分子平均面积Acmc相比较,发现Alimitγcmc.分析12-2-12-2-12单分子膜的表面压随时间的衰减,表明这个现象是由于表面活性剂从铺展单分子膜向水中溶解造成的,而且初始表面压越大,表面压的衰减越快.

英文摘要：

π-A isotherm of a monolayer at air-water interface for a quaternary ammonium salt type trimeric surfactant （shortly called 12-2-12-2-12） was investigated by the Langmuir balance technology. The surface tension at collapse pressure, γcollapse, and the molecular limited area, Alimit, were determined and compared with the surface tension of the surfactant solution at CMC concentration, γcmc. In addition, the molecular average area Acmc was calculated according to the Gibbs adsorption equation. The following relationships were found： Alimit〈Acmc and γcollapse〉γcmc. These results were related to a partial dissolution of this surfactant via the spreading of the monolayer to the water subsurface, which was shown by the decrease of the surface pressure of its monolayer with time. The higher the initial surface pressure, the rapider the attenuation of the surface tension.