Contact resonance AFM to quantify the in-plane and out-of-plane loss tangents of polymers simultaneously

Contact resonance atomic force microscope (AFM) methods are used to quantify the elastic and viscoelastic properties of numerous materials including polymers. More recently, U-shaped AFM thermalevers have been developed to allow the local heating of samples, and the resonances of these probes are much more complex. These probes also allow the in-plane and out-of-plane tip-sample motion to be excited independently at the same location using a Lorentz force excitation. Here, such a probe is used to determine the in-plane and out-of-plane viscoelastic properties at the same location. The approach is demonstrated with respect to the indentation and shear loss tangents on high-density polyethylene and polystyrene.