Measurement of mechanical properties of polymer nanospheres by atomic force microscopy: effects of particle size

The mechanical properties of polymer nanoparticles as a function of their size were measured using atomic force microscopy (AFM). A novel protocol was developed, and the elastic modulus of individual nanospherical particles was computed from AFM ´force-distance´ mapping curves. To eliminate the tip geometry, hemispherical tungsten (W) tip was fabricated using a focused ion beam under controlled conditions and was used as an indenter. It is found that the nanospherical polypropylene (PP) particles have a higher elastic modulus compared to the bulk. The results corroborate the robustness of our experiments as the analogous results for bulk match well with the literature.