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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 8: POSTER: Polymer Physics

CPP 8.11: Poster

Monday, March 26, 2007, 16:00–18:00, Poster B

Phase contrast in AFM images of hard-soft polymeric systems — •Albrecht Petzold, Klaus Schröter, and Thomas Thurn-Albrecht — Martin-Luther-University Halle-Wittenberg, Institute of Physics, Experimental Polymer Physics

Tapping mode atomic force microscopy (TMAFM) is widely used to obtain height and phase images of heterogeneous polymeric systems. The influence of sample properties and imaging parameters on the phase image is still an active area of research. We here present a detailed study about the origin of the phase contrast in polyethylene (PE) as a typical semi-crystalline polymer with a liquid like amorphous phase. The phase signal obtained during imaging of PE is compared to measurements on hard and soft model systems, namely glassy polystyrene (PS) and crosslinked poly(dimethylsiloxane) (PDMS). Force spectroscopy curves of both model polymers were taken to obtain amplitude and phase information depending on the tip-sample distance. The phase signal of PE can be qualitatively understood in comparison to the different phase-distance curves obtained on PS and PDMS. Additionally the influence of several imaging parameters, like excitation frequency, free amplitude and stiffness of the cantilever on the shape of the force spectroscopy curves was investigated. As a result empirical suggestions for imaging of semi-crystalline polymers are made.