Subsurface imaging of soft polymeric materials with nanoscale resolution.

Nondestructive depth-resolved imaging of ∼20-nm-thick surface layers of soft polymeric materials is demonstrated using amplitude modulation atomic force microscopy (AM-AFM). From a map of amplitude-phase-distance curves, the tip indentation into the specimen is determined. This serves as a depth coordinate for reconstructing cross sections and volume images of the specimen's mechanical properties. Our method reveals subsurface structures which are not discernible using conventional AM-AFM. Results for surfaces of a block copolymer and a semicrystalline polymer are presented.