Chapter 9 - Application of Atomic Force Microscopy for the Study of Tensile and Microrheological Properties of Fluids

Abstract

This chapter explains the application of atomic force microscopy (AFM) for the study of tensile and microrheological properties of fluids. AFM is one of the most successful techniques for the characterization of surfaces and is routinely used to describe structural details with nanoscale resolution. The ability of AFM to differentiate between local mechanical properties is well known. The atomic force microscope is clearly a powerful tool for the investigation of forces which govern the mechanics of processes occurring at or below the microscale, and the exceptional ability of atomic force microscopy to determine forces associated with the microscope deformation and flow of fluids is discussed. An understanding of the rheology of complex fluids is of fundamental importance in many practical engineering and biomedical applications. The rheological behavior of thin liquid films is an important aspect of lubrication and printing—processes that often involve mesoscale thickness films undergoing rapid deformation between separating surfaces. The nanorheological properties of polymeric liquids can be obtained by adapting techniques such as an surface force apparatus (SFA) or an AFM to act in a dynamic mode. However, the results of AFM studies are often more difficult to interpret than those derived from SFA experiments due to uncertainties about the zero separation distance, the influence of probe asperities, and torsional deflections.