官能团对自组装分子膜摩擦特性的影响

Effects of functional groups on the friction properties of self-assembled monolayers

在原子力显微镜上,对分子链长相同、官能团不同的两种自组装分子膜的摩擦特性进行了研究,分析了载荷和滑动速度对自组装分子膜摩擦特性的影响.结果表明:自组装分子末端官能团的化学活性越强,形成的自组装分子膜的团簇特征越显著;对于两种短链自组装分子,摩擦力随着载荷的增大而增大,而滑动速度的影响在自组装分子末端官能团化学活性较大时才表现出来.形成结构稳定的自组装分子膜后,摩擦力比成膜初期的自组装分子膜显著降低,具有减摩效应.具有较强化学活性官能团的自组装分子膜,当载荷增加到一定值以后,会失去减摩效应,其化学活性越强,摩擦力越大.

The friction properties of two kinds of self-assembled monolayers (SAMs) with the same length of molecule chain and different functional groups were investigated. The effects of load and sliding velocity on the friction characteristics of SAMs were analyzed. The results indicate that the stronger the chemical activity of functional group in self-assembled molecules is, the more remarkable the SAMs cluster topography characteristics are. The friction forces increase with increasing the loads for these two self-assembled molecules with short chain. However, the effects of sliding velocity on the friction force appear when the chemical reactivity of functional group in self-assembled molecules is strong enough. The friction forces decrease markedly after the formation of SAMs with stable structure, which exhibits anti-friction effect. The anti-friction effect disappears if the load rises to a threshold for SAMs with stronger active functional group. The stronger the chemical activity of functional group in self-assembled molecule is, the larger the friction forces are.