Regensburg 2019 – wissenschaftliches Programm

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O: Fachverband Oberflächenphysik

O 10: New Methods and Developments II: Scanning Probe, Spectroscopic, and Diffraction Techniques

O 10.6: Vortrag

Montag, 1. April 2019, 16:15–16:30, H3

Sensing in-plane and out-of-plane nanomechanical Surface and Subsurface Properties of Polymers — •Anna Lisa Hawlitschek and Christian Dietz — TU Darmstadt

Bimodal atomic force microscopy enables the quantitative nanomechanical analysis of heterogeneous polymers. The technique is based on the simultaneous excitation and detection of two different cantilever eigenmodes. Depending on the type of the oscillation modes (flexural or torsional), out-of-plane elastic and dissipative sample properties or the in-plane shear behavior can be analyzed. Here, a trimodal approach was developed where in addition to the first flexural eigenmode, the second flexural eigenmode as well as the first torsional eigenmode were excited. The indentation depth of the tip into the sample surface could be controlled by the first flexural oscillation amplitude used for the topographical feedback. The frequency shifts of the second flexural and the first torsional eigenmode provided measures for the elastic moduli and the shear forces, respectively, using a frequency modulation setup in constant amplitude mode. Thus, dissipative interactions could be derived from the drive amplitudes of the second flexural and the first torsional eigenmodes. It was demonstrated that differences in the elastic behavior in in- and out-of-plane direction can be examined on heterogeneous polymers (elastomeric polypropylene and polystyrene-block-polybutadiene diblock copolymer) using this trimodal approach with high lateral and depth precision.