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表面活性素是一类具有较强表面活性的微生物脂肽类化合物, 能在空气/水界面形成不溶性单分子膜.利用Langmuir膜天平测定了表面活性素单分子膜的压缩-扩张循环曲线, 发现单分子膜在经历了“平台区”后出现较大的迟滞环, 迟滞环的形状与亚相pH有关. 将“平台区”的单分子膜转移到云母表面后, 用原子力显微镜(AFM)和扫描电子显微镜(SEM)均观察到高度达几十至数百纳米的表面聚集体, 说明表面活性素在单分子膜的“平台区”伴随着自聚集. 研究结果表明, 表面活性素单分子膜在空气/水界面的迟滞现象是分子浸入亚相和形成三维表面聚集体共同作用的结果.
Surfactant is a type of lipopeptide with high surface activity and can form insoluble monolayer at the air / water interface.The compression-dilation cycle of surfactant monolayer was measured by Langmuir membrane balance and found that The monolayer appears a large hysteresis loop after experiencing the “platform zone”, and the shape of the hysteresis loop is related to the pH of the subphase. After the monolayer of the “platform zone” is transferred to the mica surface, the atomic force microscope (AFM) and scanning electron microscopy (SEM), the surface aggregates with the height up to tens to hundreds of nanometers were observed, indicating that the surface active elements were self-aggregated in the “plateau” of the monolayer. The hysteresis of the surfactant monolayer at the air / water interface is the result of the interaction of molecules immersed in the subphase and the formation of three-dimensional surface aggregates.