Join us for the next NEMI platform meeting in which Marijn van Huis give a colloquium.
Date: April 19th
Advances in Liquid Phase Electron Microscopy: Imaging Strategies for Soft Materials and Controlled Motion of Nanoparticles
In-situ cells developed for the transmission electron microscope (TEM) allow performing experiments on nanoscale materials in liquids and gases, even while heating or under application of electric fields, while imaging them at near-atomic resolution. Of these two, in particular liquid cell TEM (LC-TEM) imaging is particularly sensitive to e-beam effects . In this seminar I will discuss recent progress made at Utrecht University in the imaging of induced transitions. The first model system is p-NIPAM, a thermoresponsive biocompatible polymer that reversibly compresses when heated from room temperature to a temperature of 40 °C and vice versa. When immersed in water and thus swollen, the density of p-NIPAM is almost the same as that of water, while it is extremely sensitive to e-beam irradiation. Eventually a suitable approach was found and the thermoresponsive response was successfully imaged . The second model system is a ‘rattle particle’ consisting of a mobile core particle inside a larger silica shell where the porous shells are filled with liquid. Depending on the salt concentration in the liquid, the potentials between the core and shell could be adapted to confine the core particle at the center of the shell, or be adapted in such a way that the core particle could explore nearly the entire volume of the spherical cavity . Finally, preliminary results on the application of an AC electric field on the rattles show that the direction of the motion of the cores, either parallel or orthogonal to the field, could be controlled depending on the frequency of the applied field.
 T.A.J. Welling, S. Sadighikia, K. Watanabe, A. Grau-Carbonell, M. Bransen, D. Nagao, A. van Blaaderen, M.A. van Huis, ‘Observation of undamped 3D Brownian motion of nanoparticles using liquid-cell scanning transmission electron microscopy’, Part. Part. Syst. Charact. 37 (2020), 202000003, pp 1-10. DOI: 10.1002/ppsc.202000003.
 A. Grau-Carbonell, F. Hagemans, M. Bransen, N. Elbers, R. J. A. van Dijk-Moes, S. Sadighikia, T. A. J. Welling, A. van Blaaderen, M. A. van Huis, ‘Direct in-situ characterization of the thermoresponsive and cononsolvent behavior of Poly(N-isopropylacrylamide) microgels and shells with nanometer resolution’, in preparation.
 T.A.J. Welling, K. Watanabe, A. Grau-Carbonell, J. de Graaf, D. Nagao, A. Imhof, M.A. van Huis, A. van Blaaderen, ‘Tunability of Interactions between the Core and Shell in Rattle-Type Particles Studied with Liquid-Cell Electron Microscopy’, ACS Nano 15 (2021) 11137-11149. DOI: 0.1021/acsnano.1c03140