Tribological properties of ultra-thin functionalized polyethylene film chemisorbed on Si with an intermediate benzophenone layer

Abstract

In this study, an ultra-thin (~20 nm) functionalized polyethylene (fPE) film is successfully attached to Si substrate via a reactive benzophenone (Ph 2CO) layer. The presence of fPE promotes wear durability of Si/Ph 2CO/fPE to 1,000 cycles compared with 100 cycles for Si/Ph 2CO and nearly zero wear life for bare Si in a ball-on-disk (4-mm-diameter Si 3N 4 ball) wear test under 40 mN applied normal load and 500 rpm sliding speed. As an enhancement to the wear life, perfluoropolyether (PFPE) is applied as a top mobile lubricant layer coated onto Si/Ph 2CO and Si/Ph 2CO/fPE. A significant improvement in the wear durability is observed as Si/Ph 2CO/PFPE fails at 250,000 cycles and Si/Ph 2CO/fPE/PFPE does not fail until one million cycles. Si/Ph 2CO/fPE/PFPE can withstand a minimum applied load of 150 mN at a sliding speed of 0.052 ms -1 without failure, providing a PV (pressure x velocity) limit of greater than 106.6 MPa ms -1. © 2010 Springer Science+Business Media, LLC.