Nanoscale Characterization of Coatings Surface Degradation With Tapping Atomic Force Microscopy.
Nanoscale Characterization of Coatings Surface
Degradation With Tapping Atomic Force Microscopy.
Nguyen, T.; Gu, X.; VanLandingham, M.; Ryntz, R.;
Nugyen, D.; Martin, J. W.
Adhesion Fundamentals: From Molecules to Mechanisms and
Modeling. Adhesion Society Annual Meeting, 26th.
Proceedings. February 23-26, 2003, Myrtle Beach, SC,
508-510 pp, 2003.
coatings; microscopy; degradation; atomic force
microscopy; chemical heterogeneity; relative humidity;
humidity; phase contrast; friction contrast
Surface characteristics of a polymer coating, such as
gloss, and their changes with weathering depend strongly
on surface topography and morphology. Therefore, data on
early physical changes of coatings surface can provide
valuable information for not only understanding the
degradation mode but also for predicting long term
performance. Atomic force microscopy (AFM) is well
suited for studies of early coatings degradation, as
demonstrated recently. This paper presents examples
from the research in our laboratory on the use of both
the phase and topographic imaging in tapping mode AFM
(TMAFM) to investigate early surface physical
degradation of coatings exposed to weathering
environments. In tapping mode AFM, the probe is
oscillated at a frequency near resonance. As the tip
approaches the sample, the tip-sample interactions
change the amplitude, resonance frequency, and phase
angle of the oscillating probe. Detection of the
amplitude and phase changes during scanning provides the
topographic and phase images, respectively. Phase
imaging in TMAFM is sensitive to both mechanical and
chemical properties of the surface and tip-sample