Control of friction and wear is a ubiquitous challenge in numerous machined interfaces ranging from biomedical implants, to engines, to nano- and micro-scaled devices, with the energy losses associated with friction and wear having significant impacts on the economies of the world. Notably, the combined energy losses and the associated system downtime due to friction and wear, contribute to an estimated loss of ~$200 billion/year in the United States alone. A ubiquitous challenge in many of these applications is how to control the wear that occurs in sliding contacts, which are dominated by the interactions between nanoscaled surface asperities, where the high pressures and shear forces that are experienced can result in increased friction and ultimately lead to device failure through tribochemical breakdown. Here, 2D nanomaterials, such as graphene, have been shown to offer potential solutions. However, as with all lubrication schemes, obtaining an atomic/molecular scale understanding of the energy dissipation and associated tribochemical reaction mechanisms that occur at the nanoscopic asperity-asperity contacts in such interfaces, is paramount for their rational design and implementation. It has previously been shown that nanoscopic surface roughness can introduce bond strain in graphene that can alter its local chemical reactivity, which can likely make these regions of high strain susceptible to tribochemical breakdown. To explore these effects in a systematic fashion, we have created patterned arrays of perfluorophenylazide (PFPA) silanes in a background of octadecyltrichlorosilane (OTS) covered by single layer graphene to examine how applied force by AFM influences the  local reactivity of PFPA with the graphene surface. The design of the test platforms for following this reaction, along with our initial studies of the load dependence on the chemical reactivity of graphene with PFPA will be described.

Probing the load/strain dependent reaction of perfluorophenylazide (PFPA) with graphene

255th National Meeting (2018)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.