The Static and Dynamic Responses of Binary Mixture Perfluoropolyether Lubricant Films— Molecular Structural Effects

Abstract

Static and dynamic properties of single-component perfluoropolyether (PFPE) lubricants have been studied for optimal lubricant selection by examining the molecular conformations that influence the thickness and the mobility for the self-healing capability in lubricant nanofilms. In this paper, we examine the physiochemical properties of the mixture of these two PFPEs using molecular dynamics (MD) simulations to find an optimal blend ratio to meet the stringent requirements for disk lubricants of ultra-low head media spacing (HMS). A coarse-grained, bead-spring model was used to model the polymer nanoblends using functional and nonfunctional PFPEs. We examined the static and dynamic responses of binary PFPE films as a function of the molecular structures including end-group functionality. The effect of the functional end-group on the static structures was examined by simulating the parallel and perpendicular components of the radius of gyration. The dynamic responses of various PFPE nanoblends were also simulated by explicitly calculating the self-diffusion coefficient of a tagged molecule. Polydispersity effect on nanoblends was also examined.