Adhesion and Friction Properties of Polymers at Nanoscale: Investigation by AFM

Abstract

Friction and adhesion of model elastomers are quantified at two different scales: at nanoscopic scale, using atomic force microscopy (AFM) and at macroscopic scale, using a tack test and a translation tribometer. The objective is firstly to find a correlation between nanoscale adhesion and friction, by comparing the influence of structural parameters such as crosslinking degree and presence of free chains. The scope is also to verify if friction and adhesion behaviors are comparable at both scales. Experimental results underline the major role of molecular parameters such as degree of crosslinking and length und content of free and pendant chains. However, their effect on nano and macroscale properties is different. Conceptual schemes are proposed to describe the complex interfacial molecular mechanisms, especially chain adsorption onto the tip which seems to govern nanoscale friction and adhesion. Further friction studies, performed on polymers in contact with hydrophilic and hydrophobic tip and substrate allow us to underline the complex competition between interfacial interactions and polymer surface rheological behavior.