Interaction and Viscoelastic Deformation of Polymeric Surfaces Measured with the Atomic Force Microscope

Methods are described for the measurement and analysis of deformable surfaces with the atomic force microscope (AFM). It is shown how to obtain the zero of separation and how to calibrate the photo-diode for quantitative force measurement [1]. The properties of viscoelastic materials (relaxation times, Youngs moduli) may be extracted by modeling particular sorts of force measurements [2]. Results are shown for a biopolymer agar [3], and for a polyelectrolyte polydimethylsiloxane [4], both of which are viscoelastic, and for polystyrene, which is elastic [5]. The potential for using the AFM as a nanorheometer is discussed. \newline \newline [1] P. Attard, ``Friction, Adhesion, and Deformation: Dynamic Measurements with the Atomic Force Microscope'', J. Adhesion Sci. Technol. 16, 753--791 (2002). \newline [2] P. Attard, ``Interaction and Deformation of Viscoelastic Particles. Non-adhesive Particles'', Phys. Rev. E 63, 061604 (2001) \newline [3] J. W. G. Tyrrell and P. Attard, ``A Viscoelastic Study Using and Atomic Force Microscope Modified to Operate as a Nanorheometer'', Langmuir 19, 5254--5260 (2003) \newline [4] G. S. Gillies, C. A. Prestidge, and P. Attard, ``An AFM Study of the Deformation and Nano-rheology of Cross-Linked PDMS Droplets'', Langmuir 18, 1674--1679 (2002) \newline [5] M. W. Rutland, J. W. G. Tyrrell, and P. Attard, ``Analysis of Atomic Force Microscopy Data for Deformable Materials'', J. Adhesion Sci. Technol. 18, 1199--1216 (2004)