Graduation Year
2015
Document Type
Dissertation
Degree
Ph.D.
Degree Name
Doctor of Philosophy (Ph.D.)
Degree Granting Department
Physics
Major Professor
William Garrett Matthews, Ph.D.
Committee Member
Pritish Mukherjee, Ph.D.
Committee Member
Inna Ponomareva, Ph.D.
Committee Member
Jianjun Pan, Ph.D.
Keywords
Nanoindentation, Lateral Force Microscopy, Size, Elastic Modulus, Adhesion Force
Abstract
Friction between nanoscale objects has been a subject of great interest and intense research effort for the last two decades. However, the vast majority of the work done in this area has focused upon the sliding friction between two rigid, atomically smooth surfaces. Thus the parameter most explored has been the corrugation in the atomic potentials and how this affects the force required to slide one object across another. In truth, many nanoscale objects whose translation force is of practical interest are more spherical in nature. We hypothesize that the factors that determine the translation force will be related, not only to the interfacial adhesion, but also to the mechanical properties of the translating object and its underlying surface. The dependence on these quantities of the friction is not known. In this dissertation we have utilized Atomic Force Microscopy and Force Spectroscopy to study the tribological properties of submicron scale polymeric particles to explore how the friction between these submicron spherical objects translating over planar substrates is related to interfacial energy and the mechanical properties for these particles. A technique for modifying the mechanical properties was developed and used to provide a set of samples over which we had control of the elastic modulus without corresponding changes in the chemical bonds. The modified mechanical properties were tested against the Flory-Rehner theory. Lateral force microscopy was used to measure the force required to translate asymmetric, nanoscale particles of controlled size, surface chemistry and moduli. Silicon wafers were used as the substrate. The effects of work of adhesion, elastic modulus of polystyrene microspheres, and contact radius between particle and substrate have been studied for the different modes of particle translation under an external force.
Scholar Commons Citation
Verma, Himanshu Kumar, "Nanomechanical and Nanotribological Characterization of Sub-Micron Polymeric Spheres" (2015). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/5791
