Evaluation of nano-frictional and mechanical properties of a novel Langmuir-Blodgett monolayer/self-assembly monolayer composite structure

TL;DR

This study fabricates a novel SA/APS composite monolayer using Langmuir-Blodgett and self-assembly techniques, evaluating its nano-frictional and mechanical properties, revealing enhanced lubrication and wear resistance suitable for nano/microelectromechanical systems.

Contribution

It introduces a new SA/APS composite structure with improved tribological properties, combining Langmuir-Blodgett and self-assembly methods for potential MEMS lubrication.

Findings

Heated SA-APS bilayer follows DMT contact model.

Frictional forces are load-dependent and affected by adhesion.

Heated composite shows superior lubrication and wear resistance.

Abstract

A novel stearic acid (SA)/3-aminopropyltrethoxysilane (APS) composite structure was fabricated using the combined method of the Langmuir-Blodgett technique and self-assembly monolayer (SAM) technique. Its frictional, adhesive properties and interface contact types between the atomic force microscope tip and the samples were evaluated based on Amonton's laws and the general Carpick's transition equation, respectively. The results showed that the tip-sample contacts corresponded to the Johnson-Kendall-Robert/Derjaguin-Muller-Toporov (DMT) transition model for SiO2, APS-SAMs, and the unheated SA-APS composite structure, and for the heated SA-APS bilayer to the DMT model. Frictional forces for the four samples were linearly dependent on external loads at higher loads, and at lower loads they were significantly affected by adhesive forces. Frictional and scratching tests showed that the heated SA-APS composite structure exhibited the best lubricating properties and adhesion resistance ability, and its wear resistance capacity was greatly improved due to the binding-mode conversion from hydrogen bonds to covalent bonds. Thus, this kind of composite bilayer might be promising for applications in the lubrication of nano/microelectromechanical systems. I.