Dr. Ingo Lieberwirth

The electron microscopy group at the MPI-P is an integral part of the scientific infrastructure of the institute. It´s our task to support the synthesis of polymers and tailored materials with electron microscopical characterization methods. For this we operate a versatile equipment and offer the necessary expertise for planning, conducting and interpretation of the electron microscopical measurements. We are focused – but not limited- to the examination of organic and inorganic nanoparticles, polymers and other, beam sensitive soft matter, biological systems like cells and tissue as well as any combination of these materials.
The equipment of the EM group comprises Scanning Electron Microscopes (SEM) as well as Transmission Electron Microscopes (TEM). Furthermore we are operating several preparation devices to make the optimal samples for the respective examination.

One of our Research projects at the EM-Group of the MPI-P is the development of a correlative method to combine information for light- and electron microscopy. This project is supported by the Sonderforschungsbereich 1066 – “Nanodimensional polymeric therapeutics for tumortherapies”. Here we examine how polymer nanoparticles interact with living cells. For this, the cells were incubated with the Nanocarriers and subsequently fixed by high pressure fixation (HPF). For electron microscopy these vitrified samples were then further prepared by means of freeze substitution and ultramicrotomy.

A further research area on which the EM-Group is working is the crystallization of polymers which have a precise, equidistant distribution of defects along the chain. Due to the increased defect density within the polymer crystal, its beam sensitivity increases significantly. Furthermore, the lateral size of the crystals is in the order of < 500 nm and thus inaccessible for X-ray structural examination. Hence, we are specialized to examine beam sensitive crystals to extract any accessible information on their crystal structure.

Within the last years the EM-Group at the MPI-P examined a multitude of different nanoparticles, with a focus on soft matter particles. It´s one of our main goals to minimize the preparation artefacts for EM of these particles. In general, cryo-TEM is the preparation of choice, because here the formation of artefacts is known to be low and manageable. However, cryo-TEM is a time consuming preparation method and thus not adequate for a high sample throughput, especially because for any new particle system new cryo-TEM preparation parameters needs to be adjusted. Alternatively, we developed strategies which significantly reduce preparation artefacts and simultaneously allow a high sample throughput due to easy and fast preparation methods.

Imaging of polymeric nanoparticles: Hard challenge for soft objects, Renz, P., Kokkinopoulou, M., Landfester, K. and Lieberwirth, I., Macromol. Chem. Phys., 2016, 217, 1873, DOI: 10.1002/macp.201670054

Morphology and Thermal Properties of Precision Polymers: The Crystallization of Butyl Branched Polyethylene and Polyphosphoesters, Yi-Ran Zheng, Hisachi Tien Tee, Yujin Wei, Xi-Lin Wu, Markus Mezger, Shouke Yan, Katharina Landfester, Ken Wagener, Frederik R. Wurm, and Ingo Lieberwirth, Macromolecules, 2016, 49(4), 1321–1330, DOI: 10.1021/acs.macromol.5b02581

Elimination of charge carrier trapping in diluted semiconductors, D. Abbaszadeh, A. Kunz, G.-J. A. H. Wetzelaer, J. J. Michels, N. I. Craciun, K. Koynov, I. Lieberwirth, P. W. M. Blom, Nature Materials, 2016, 15(6), 628-633, DOI: 10.1038/nmat4626

Flexible Minerals: Self-Assembled Calcite Spicules with Extreme Bending Strength, F. Natalio, T. P. Corrales, M. Panthoefer, D. Schollmeyer, I. Lieberwirth, W. E. G. Mueller, M. Kappl, H.-J. Butt, W. Tremel, Science, 2013, 339, 1298-1302, DOI: 10.1126/science.1216260