Atomic force microscopy investigation of filled elastomers and comparison with transmission electron microscopy — application to silica-filled silicone elastomers

Tapping mode atomic force microscopy experiments were conducted on silica-filled silicone elastomers. Phase images provide a good contrast between the silicone matrix and silica structures, and allow the study of silica microdispersions. However, the phase contrast is sensitive to several experimental factors, which affect the magnitude of tip-sample interactions. The dependence of the phase contrast on the free amplitude of cantilever oscillation, on the setpoint ratio, on the cantilever stiffness and on the sample modulus was investigated. The setpoint ratio was shown to be the main parameter controlling the tip-sample force, and consequently the phase contrast. By comparing the results with transmission electron microscopy experiments, the tapping mode atomic force microscopy with phase imaging is established as an easy and powerful technique for the characterization of the silica dispersion in a silicone matrix. This study opens the way for using Atomic force microscopy to get a better understanding of reinforcement in filled rubbers.