Tapping mode force microscopy imaging of elastic properties of core-shell latex particles

In this study films of core-shell-structured latex particles are investigat ed by dynamic scanning force microscopy 'tapping mode imaging'. Polymer dis persions with cores of the low-viscosity polymer poly(2-ethylhexyl methacry late) (PEtHMA) and shells of the cross-linked rubber poly(n-butyl acrylate) (PBA) were spread on a flat mica surface to form a monolayer, Topographic as well as phase images were recorded at different amplitudes and damping f actors (so-called soft and hard tapping). The topographic images show a con tinuous matrix formed by the particles, but a clear contrast of individual particles in the phase images could be obtained at high damping factors of the cantilever oscillation. The soft cores embedded in the matrix of the sh ell polymers caused a perceptible reduction of the phase of oscillation. Co nsequently, the total particle appeared soft enough because it allowed defo rmation of the soft cores below. Copyright (C) 1999 John Wiley & Sons, Ltd.