Abstract
In this paper, atomic force microscopy has been employed to investigate the surface roughness of mixed self-assembly monolayers (SAMs) with different mixing ratios in nano scale. The combination of Sader’s normal force and Carpick’s lateral force calibration methods were utilized to calculate the friction forces and friction coefficients. The results were also modified by considering B. Bhushan’s model on surface contact properties in physical or chemical aspects. Through the measurement of contact angles, adhesion forces, and friction forces on alkanethiol SAMs (C5 and C9) with different mixing ratios, the friction force is larger with mixed SAMs than that of pure SAMs, suggesting the contribution of surface roughness on friction force. The mixing ratios also affect the friction force, and the minimum friction appears in the mixing ratio 1 to 1, indicating the different cluster formation in different mixing ratios. Further study is still undergoing to in detail investigate the size, distribution and density of those SAMs clusters under different mixing conditions.