Tuning super-lubricity via molecular adsorption
Tuning super-lubricity via molecular adsorption
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DOI：
10.1016/j.apmt.2022.101615
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发表时间：
2022
影响因子：
8.3
通讯作者：
Zhe Chen;Seong H. Kim
中科院分区：
文献类型：
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作者：
Zhe Chen;Seong H. Kim
消除摩擦的状态被称为超润滑，是非常理想的，以减少寄生能量损失。然而，如果没有有效的方法来开启和关闭超润滑性，将很难充分发挥其在工程应用中的潜力。本文报道了非晶二氧化硅尖端和石墨基面之间的纳米级超润滑可以通过物理吸收环境中的各种分子来调节。其中，在正戊醇蒸汽中可进一步降低约54%，而在水和苯酚蒸汽中可分别提高约25倍和45倍。蒸汽分子通过吸附在二氧化硅表面并被夹带到滑动界面来影响摩擦。根据吸附分子的结构，可以推断出具有高构象熵的吸附剂可以抑制界面通约化并增强超润滑性，而能够促进与石墨表面相应相互作用的吸附剂可以增加摩擦。这一发现为按需控制进入和脱离固体界面超润滑状态的摩擦提供了基本原理。
The state of vanishing friction known as super-lubricity is highly desirable to reduce parasitic energy loss. However, without efficient means to turn on and off the super-lubricity, it would be difficult to realize its full potential in engineering applications. Here we report that the nanoscale super-lubricity between amorphous silica tip and graphite basal plane can be tuned by physisorbing various molecules from the environment. In particular, the super-low fiction can be further reduced by about 54% inn-pentanol vapor, but increases by around 25 and 45 times in water and phenol vapor respectively. The vapor molecules influence the friction by adsorbing onto the silica surface and being entrained into the sliding interface. Based on the structures of adsorbed molecules, it could be deduced that adsorbates with high conformational entropy can suppress the interfacial commensuration and enhance the super-lubricity, while the ones that can facilitate commensurate interactions with the graphite surface increase friction. This finding provides the basic principle enabling on-demand control of friction into and out of the super-lubricious state of solid interface.