Focused ion beam milling and scanning electron microscopy characterization of polymer + metal hybrids

Abstract

Hybrid materials were prepared by mixing commercial polymers with micrometric metal powders. The polymer matrix used was low density polyethylene (LDPE). We have used aluminum spheres with the average diameter of 1 μm. The particle concentration in the matrix was varied from 0.5 wt.% to 10 wt.%. Scanning electron microscopy (SEM) was used to investigate the particle dispersion on the surfaces of the microhybrids. Focus ion beam (FIB) milling was used to create a transversal cut in the material. SEM imaging was performed before, during and after ion milling to investigate the milling process. The hybrid surfaces are better characterized by backscattered electrons than by the secondary electrons; in the former case a higher contrast difference between the matrix and the dispersed phase allows us to identify the positions of the metal particles inside the matrix. Our SEM + FIB technique combination is useful for hybrids based on polymer matrices. Transversal cross-sections made with the ion beam allowed us to observe the dispersion of the metal particles inside the polymer. Although there can be certain problems during milling, such as heating provoking damage in the material, it is possible to optimize the experimental parameters so as to eliminate the problems. Our microhybrids have a uniform dispersion of the Al powder throughout the material.