Friction behavior of rough polydimethylsiloxane surfaces under hydrophobic polymer aqueous solution conditions

Investigating the frictional behavior of polydimethylsiloxane (PDMS) with well-controlled roughness in complex fluids is important for biological and chemical applications. In this paper, we adopt an aqueous solution of a charged, hydrophobic acrylate copolymer as a lubricant. The scaling laws between the coefficient of friction (CoF) and the roughness of PDMS, as well as the concentration of the polymer solution in different lubrication regimes, are obtained. In the boundary lubrication regime, surface roughness and lubricant rheological behavior both remarkably influence the CoF. Moreover, the product of the CoF in the boundary regime and the velocity of the boundary-mixed transition is independent of roughness. A full lubricant film forms and shear thinning behavior dominates in the hydrodynamic lubrication regime. Frictional behavior in this tribological system has been successfully regulated. We hope to establish the optimal match of surface roughness and the rheological behavior of lubricant and unveil the mechanism behind the friction phenomenon.

Automated summary

This study investigates the frictional behavior of PDMS with controlled roughness in complex fluids using a charged, hydrophobic acrylate copolymer solution as a lubricant. The scaling laws between the coefficient of friction (CoF) and the roughness of PDMS, as well as the concentration of the polymer solution in different lubrication regimes, are explored. Surface roughness and lubricant rheological behavior significantly influence CoF in the boundary lubrication regime, while a full lubricant film and shear thinning behavior dominate in the hydrodynamic lubrication regime. The optimal match of surface roughness and lubricant rheological behavior is sought to regulate frictional behavior in this tribological system and uncover the underlying mechanism.