Critical separation distance needed to form weak menisci between the head and the disk — A molecular simulation study

Abstract

An NVT Monte Carlo (MC) simulation for non-polar perfluoropolyether (PFPE) Z has been performed using a Rouse-like algorithm applied to a simplified bead-spring off-lattice polymer model. Meniscus bridge formation between two parallel solid surfaces from 2 nm films on the bottom surfaces has been observed for several separation distances (3, 4, 6 and 8 nms). Simulations are performed with approximately 4000 and 2000 gs/mol molecular weights under the assumption of room temperature and atmospheric pressure conditions. First, ultrathin liquid films (melts) of PFPE of 2 nm thickness on the solid carbon surfaces have been thermalized. Top solid surfaces at several separation distances (3, 4, 6 and 8 nms) have been activated over these ultrathin films at separate simulation platforms and the films have been allowed to form menisci between the top and the bottom surfaces. Minimum volume fraction, adhesive and cohesive forces in the fully formed menisci between the two parallel solid surfaces have been observed.