(3ck) The Effect of Interfacial Interactions of Polymers On Friction and Adhesion

Friction and adhesion are phenomena that have grown in interest as a result of developments in research into both solid and fluid interfaces.  Achievements in the field of nanoscale devices have increased demand for improved lubricants on that length-scale, as the dominance of surface effects makes friction and adhesion of particular concern.  These factors also have important contributions in fluid flow, as advancements in superhydrophobic surfaces have allowed for significant levels of slip and drag reduction.  In both areas of research, the influence of polymers on interfacial interactions has the potential for reducing friction and adhesion, thus resulting in improved conditions for a wide range of applications.

                For this poster presentation, I will discuss efforts to apply polymeric solutions to both fields of research to create conditions of low friction and adhesion.  Specifically in terms of solid friction, thin films of polydimethylsiloxane (PDMS) networks tethered to self-assembled monolayers (SAM) were developed to function as optimal microscale lubricants.  These PDMS-SAM hybrids were found to exhibit extremely low friction coefficients, as low as 0.0012, which is the lowest ever recorded for a dry lubricant.  The friction properties were determined to result from low shear stress and dramatically small contribution of adhesion to the friction force.  In investigating fluid friction, polymeric flow over superhydrophobic surfaces was studied in an attempt to enhance the drag reduction and slip phenomena that can occur in each separate component.  Interfacial rheometry and microfluidic measurements were conducted to determine the slip length, fluid profile, and friction properties.  Overall, I will discuss results and analysis in the context of previous friction and adhesion studies, as well as potential future work on drag reduction and lubrication experiments and applications.