Frictional Properties of Organosilane Self-Assembled Monolayer in Vacuum
Frictional Properties of Organosilane Self-Assembled Monolayer in Vacuum
复制标题
有机硅烷自组装单层膜在真空中的摩擦性能
DOI：
10.1143/jjap.40.4344
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发表时间：
2001
影响因子：
1.5
通讯作者：
O. Takai
中科院分区：
文献类型：
--
作者：
Kazuyuki Hayashi;H. Sugimura;O. Takai
采用横向力显微镜（LFM）研究了甲基(CH3)-和氟甲基（CF3）端自组装有机硅烷单层膜（sam）的摩擦性能。以n-十八烷基三甲氧基硅烷或十六氟-1,1,2,2-四氢-1-三甲氧基硅烷为前驱体，采用化学气相沉积的方法在Si衬底上制备了sam。尽管端为cf3的SAM比端为ch3的SAM更疏水，但由于F原子的强电子负性，端为cf3的SAM比端为ch3的SAM吸附了更多的水。因此，LFM中的毛细力效应在端接cf3的SAM上表现得更为明显。除了CH3和CF3基团之间摩擦性能的内在差异外，CH3-和CF3端端SAM之间毛细力的差异是导致CF3端端SAM在空气中受到更大摩擦力的原因。随着温度的升高，端部为CH3-和cf3的SAMs由于分子振动的增加而变得更加润滑。此外，这两种SAMs都非常坚固，即使在300°C的温度和600 nN的负载力下，探针在真空中扫描也没有引起损伤。
Frictional properties of methyl (CH3)- and fluoromethyl (CF3)-terminated organosilane self-assembled monolayers (SAMs) have been studied by lateral force microscopy (LFM). The SAMs were prepared on Si substrates by means of chemical vapor deposition using n-octadecyltrimethoxysilane or heptadecafluoro-1,1,2,2-tetrahydro-1-trimethoxysilane as a precursor. In spite of the fact that the CF3-terminated SAM was more hydrophobic than the CH3-terminated SAM, the CF3-terminated SAM was adsorbed a larger amount of water than the CH3-terminated SAM because of the strong electron negativity of F atoms. Consequently, the capillary force effect in LFM appeared more distinctly on the CF3-terminated SAM. The difference in capillary force between the CH3- and CF3-terminated SAMs was responsible for greater friction forces in air on the CF3-terminated SAM, in addition to the intrinsic difference in frictional properties between the CH3 and CF3 groups. With increasing temperature, CH3- and CF3-terminated SAMs became more lubricant due to more increasing molecular vibration. Furthermore, both SAMs were so robust that no damage was induced by probe scanning in vacuum even at a temperature of 300°C and an applied load force of 600 nN.