Mingwu Bai

Wettability and Nanotribological Property of Multiply Alkylated Cyclopentanes (MACs) on Silicon Substrates

The geometrical microstructure together with the chemical composition of the surface governs the wettability of solid surfaces, which is very important in the study of nanoadhesion and nanofriction properties of surfaces. Multiply alkylated cyclopentane(MAC), a novel hydrocarbon mobile lubricant, was deposited on silicon by a dip-coating method. In order to investigate the influence of the surface microstructures on the wettability of MACs, silicon substrates were treated by different cleaning and etching processes. Measurements of an atomic force microscope and a contact angle meter indicate that the wettabilities of MACs on the hydroxylated silicon and the hydrogenated silicon are better than the wettability on the cleaned silicon, and that superiority is mainly caused by topological structure changes of the surface. Furthermore, the nanoadhesion and nanofriction properties were investigated. The different behaviors in adhesion and friction forces are due to the different surface energies of these silicon substrates.

Nanotribological properties of precision-controlled regular nanotexture on H-passivated Si surface by current-induced local anodic oxidation

Nano-sized textures resulted from localized electrochemical oxidation by using atomic force microscopy (AFM) were fabricated on H-passivated Si surface. In this paper, the fabrication and nanotribological properties of nanotexture by local anodic oxidation (LAO) on H-passivated Si surface are presented. A special attention is paid to find the relation between the size of oxide nanotexture and operational parameters such as tip-sample pulsed bias voltage, pulsewidth, and relative humidity to fabricate oxide nanotexture. The nanotribological properties were investigated by a colloidal probe. The results indicate that the nanotextures exhibited low adhesion and greatly reduced friction force at nanometer scale.

Precise Positioning of Lubricant on a Surface Using the Local Anodic Oxide Method

This letter describes a new method for the precise positioning of a lubricant on a surface. The nanometer-sized patterns are first fabricated using the atomic force microscopy (AFM)-based local anodic oxide (LAO) method. Multiply alkylated cyclopentanes (MACs) serving as lubricant matrix layers on nanopatterns of silicon dioxide are fabricated. By controlling the velocity of pull-off and solution conditions, we selectively immobilize MACs on the patterned areas using the dip-coating method. In our study, AFM is used for both fabrication and characterization. AFM-LAO allows the fabricated patterns to be altered in situ without the need to change masks or repeat the entire fabrication process. Furthermore, the nanotribological characterization of lubricant matrix layers on the nanopatterns was investigated with a colloidal probe.