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M. Khorasani, D. Silbernagl, D. Platz, H. Sturm:
"Insights into Nano-Scale Physical and Mechanical Properties of Epoxy/Boehmite Nanocomposite Using Different AFM Modes";
Polymers, 11 (2019), 235; 1 - 19.

Understanding the interaction between nanoparticles and the matrix and the properties
of interphase is crucial to predict the macroscopic properties of a nanocomposite system. Here,
we investigate the interaction between boehmite nanoparticles (BNPs) and epoxy using different
atomic force microscopy (AFM) approaches. We demonstrate benefits of using multifrequency
intermodulation AFM (ImAFM) to obtain information about conservative, dissipative and van der
Waals tip-surface forces and probing local properties of nanoparticles, matrix and the interphase.
We utilize scanning kelvin probe microscopy (SKPM) to probe surface potential as a tool to visualize
material contrast with a physical parameter, which is independent from the mechanics of the surface.
Combining the information from ImAFM stiffness and SKPM surface potential results in a precise
characterization of interfacial region, demonstrating that the interphase is softer than epoxy and
boehmite nanoparticles. Further, we investigated the effect of boehmite nanoparticles on the bulk
properties of epoxy matrix. ImAFM stiffness maps revealed the significant stiffening effect of
boehmite nanoparticles on anhydride-cured epoxy matrix. The energy dissipation of epoxy matrix
locally measured by ImAFM shows a considerable increase compared to that of neat epoxy. These
measurements suggest a substantial alteration of epoxy structure induced by the presence of boehmite.

http://dx.doi.org/10.3390/polym11020235