Elaboration and mechanical characterization of nanocomposites thin films: Part II. Correlation between structure and mechanical properties of SiO2-PMMA hybrid materials

Mechanical properties of hybrid thin films based on SiO2-PMMA materials were investigated through nanoindentation tests. We demonstrated in the part I of this paper, that nanoindentation is an appropriate technique to characterize hybrid organic–inorganic thin films. Specific procedures of analysis and the use of appropriate models allows to determine reproductive indentation modulus and hardness of the hybrid layers. The mechanical responses of nanocomposites are not only governed by the composition of the layers but also by the nature and the extent of the hybrid interface. Different layers have been studied, constituted by an inorganic and an organic phase that just be physically mixed or covalently connected. The weak (H bonds) or strong (covalent bonds) interactions generated by the hybrid interface lead to nanocomposites which exhibit different mechanical behaviours. Moreover, comparison between layers obtained by in situ inorganic polymerization in PMMA and layers obtained with preformed silica nano-particles have been also investigated to correlate the morphology of the nanocomposites with the mechanical responses.