Low dose electron tomography of novel nanocomposites for additive manufacturing

The development of new nanocomposites with added functionalities for Additive Manufacturing (AM) requires of a deep understanding of the 3D distribution of the selected nano-additives within the polymeric matrix, in order to optimize their performance. For this, electron tomography (ET) is an outstanding analysis technique that requires the material to withstand the electron exposure needed for the acquisition of several tens of images, becoming challenging for beam-sensitive materials. In this work, we analyse the parameters involved in the successful analysis by low dose ET of nanocomposites based in acrylic resins for stereolithography (SLA). Needleshape electron-transparent specimens have been fabricated by focused ion beam (FIB), minimizing surface damage due to the high energy Ga+ ions. Microscope settings for tuning the electron dose applied during the ET analysis of these nanoneedles are discussed. A phenomenological study of the effect of increasing the electron dose in the scanning transmission electron microscopy (STEM) analysis of the material has been carried out, showing that ET can be effectively performed at low electron doses. Two case studies are presented, to illustrate the relevance of these analyses in the development of nanocomposites with added functionalities. Our results have revealed the crucial role of the dose rate and of inaccuracies in the calculation of critical electron doses for the design of ET experiments.