Network Mesh Nanostructures in Cross-Linked Poly(Dimethylsiloxane) Visualized by AFM

Mesh network structures are visualized by peak force tapping atomic force microscopy on cross-linked poly(dimethylsiloxane) (PDMS) at the nanometer length scale. The images directly capture network mesh structures with mesh diameter values, from 10 to 16 nm at the free surface of PDMS. Perpendicular to the free surface, in cross-sectional areas exposed by cryo-fracturing, similar mesh structures are observed. When exposed to uniaxial stress, the circular mesh features become elongated, showing network deformation at the nanoscale, as a result of mechanical stress. Following Soxhlet solvent extraction the mesh-like appearance remains unchanged, but mesh diameter values decrease, which are attributed to the removal of non-crosslinked chains and silica filler.