Friction of Polymers: from PDMS Melts to PDMS Elastomers

Abstract

The\nslip behavior of polydimethylsiloxane (PDMS) polymer melts\nflowing on weakly adsorbing surfaces made of short nonentangled PDMS\nchains densely end-grafted to silica has been characterized. For high\nenough shear rates, slip lengths proportional to the bulk fluid viscosity\nhave been observed, in agreement with Navier’s interfacial\nequation and demonstrating that the interfacial Navier’s friction\ncoefficient is a local quantity, independent of the polymer molecular\nweight. Comparing the interfacial shear stresses deduced from these\nmeasured slip lengths to available friction stress measured for cross-linked\nPDMS elastomers, we further demonstrate the local character of the\nfriction coefficient and compare its value to the monomer–monomer\nfriction.