Nanoscale mechanics by tomographic contact resonance atomic force microscopy

Area of Science:

• Materials Science
• Polymer Physics
• Surface Science

Background:

• Characterizing polymer blend heterogeneity is crucial for understanding bulk properties.
• Atomic Force Microscopy (AFM) offers high-resolution surface analysis.
• Quantifying subsurface mechanical properties requires advanced AFM techniques.

Purpose of the Study:

• To detail surface and sub-surface features of polystyrene-polypropylene (PS-PP) blends.
• To quantify elastic modulus and mechanical dissipation using depth-dependent measurements.
• To generate tomographic reconstructions of material properties.

Main Methods:

• Utilized quantifiable depth-dependent contact resonance AFM (CR-AFM).
• Analyzed depth-dependences of contact stiffness and indentation depth.
• Employed linear fits for elastic moduli determination.
• Determined contributions of adhesive forces and viscous responses.

Main Results:

• Successfully mapped elastic moduli and mechanical dissipation with depth.
• Generated cross-sectional tomographic images of PS-PP blends.
• Quantified both short-range and long-range adhesive forces.
• Identified distinct viscous responses during adhesion and deformation.

Conclusions:

• CR-AFM provides detailed, depth-resolved mechanical characterization of polymer blends.
• The method allows for unambiguous determination of elastic properties, adhesion, and dissipation.
• Tomographic reconstructions offer valuable insights into subsurface heterogeneity.