Tribological properties of poly(amide amine) and small molecule composite self-assembled monolayers: Influence of functional group of small molecule

The small molecule and poly(amide amine) generation 4.0 composite self-assembled monolayers on silicon were prepared by a two-step process. Prepared films were characterized by ellipsometry, contact angle measurement, X-ray photoelectron spectroscope and results shown that composite films were assembled successfully. The nano- and micro-tribological properties were investigated by a commercial Multimode Scanning Probe Nanoscope IIIa and a reciprocal ball-on-disc tribotest, respectively. The friction force and friction coefficients are decreased and loads are improved efficiently when small molecule is inserted, but the difference of stearic acid and trimethoxysilane is not remarkable.

► The composite PAM/(stearic acid) SAM and PAM/trimethoxysilane SAM have been prepared successfully on silicon wafers by the two-step approach.
► The friction force and friction coefficients of composite SAMs are higher than that of small molecule, and lower than that of pure PAM SAM in nano-scale.
► The load-carrying capacities of composite SAMs are improved efficiently compared to pure SAMs.
► The differences between the two kind of composite SAMs are not remarkable.