Interfacial Debonding of Embedded Particles in Nanocomposite Systems Using Atomic Force Microscopy and Finite Element

Atomic Force Microscopy (AFM) is a widely used material characterization technique with a variety of engineering and aerospace applications. The method involves raster-scanning the surface of a sample with a probe attached to a cantilever. By tracking the probe’s deflection with a laser and photodiode, AFM creates high-resolution topographies of the specimen and can determine material properties at nano- and sub-nanometer resolutions through various measurement channels. Despite numerous innovations in AFM architecture, measurement modes, and experimental standards, achieving accurate results with AFM on heterogeneous materials, such as polymer nanocomposites (PNCs) and nanomembranes, remains a challenge. While much work has been done to identify phenomena that create artifacts in the AFM signal and cleanse AFM data from their effects, several critical parameters have not been thoroughly investigated in existing research. This paper uses finite element analysis (FEA) to investigate the effect of destructive indentation on the AFM signal. Particles of various sizes are considered, and findings regarding the effect of particle placement on the compressibility of the polymer matrix are considered in the analysis and discussed. The Hertz and Derjaguin-Muller-Toporov (DMT) contact mechanics models were used to validate the FE model and perform all calculations. The authors believe that the findings from this research will give key insights into AFM-based characterization of membranes and heterogeneous nanocomposites.