What is your “sol-gel” background ?
Trained as a general chemist at the University of Würzburg, I started doing sol-gel chemistry with my diploma thesis on silica aerogels. Fascinated by these lightweight structures, I continued working on the organofunctionalization of silica aerogels during my Ph.D. work in Würzburg, and even after moving to Vienna I was very lucky that I could still act in the stimulating and interdisciplinary research environment of the groups of Prof. Schubert (chemistry, Vienna), Prof. Fricke (physics, Würzburg) and the Fraunhofer Institute for Silicate Research in Würzburg. A DAAD fellowship allowed to even expand my expertise in the field of sol-gel processing by the incorporation of glutamate dehydrogenase in silica gels combined with the allosteric regulation of enzymatic reactions during a six month stay in the group of Prof. J.I. Zink at UCLA, USA. After receiving my Ph.D. in 1997 from the University of Würzburg, I returned to the United States (Albuquerque) in the group of Prof. C.J. Brinker. The Advanced Materials Laboratory in Albuquerque is a highly inspiring research environment and I really enjoyed working on evaporation-induced self-assembly approaches towards periodically organized porous thin films. In 1998, I returned to Europe and became a group leader for porous materials at the Vienna University of Technology. Again sol-gel processing in combination with different templating strategies was the main approach in the synthesis of our materials. Since then I got a full professorship for inorganic chemistry at Ulm University in Germany (2004) and moved recently back to Austria (2010) as the chair of materials chemistry at the Paris-Lodron University in Salzburg, Austria. Research is still largely focused on sol-gel processing in combination with other solution-based syntheses towards inorganic and organic-inorganic hybrid materials with novel structures or property profiles.
What are the main topics you are working on today?
The main focus of our current research is the investigation of synthesis – structure relationships in highly porous and high surface area, inorganic and inorganic-organic hybrid materials. High surface area materials with controlled porosity have found a wide range of applications, e.g. as supercapacitors or electrode materials for electrochemical energy storage systems, in catalysis, as sensors, in chromatographic applications, for controlled drug delivery, in biomedical applications and many more. Recently we became more and more interested in the deliberate synthesis of more complex chemical structures with a hierarchical porosity, thus multifunctional materials. Our approach typically starts from the precursor molecule, which is most often tailor-made to give certain structures, followed by playing around with the sol-gel processing conditions, and finally a thorough investigation of the structure by different analytical methods, such as electron microscopy, X-ray scattering and diffraction, porosimetry, spectroscopy, etc.
The collaborations you have initiated?
Working in the field of sol-gel chemistry it is quite clear from the beginning that you have to rely on experts in many different areas, e.g. from physics, chemistry, materials sciences or even medicine or biology. Since my diploma thesis I have strong, still ongoing collaborations with physicists, e.g. Dr. G. Reichenauer (ZAE Würzburg) or Prof. Dr. H. Peterlik (Vienna University). One exciting part in our work is that many possible applications for the different materials can be envisioned: To name just one example, we recently started a project involving the differentiation of mesenchymal stem cells on porous sol-gel coatings in cooperation with Prof. R. Brenner from the Department of Orthopaedics, at Ulm University and it is a lot of fun to learn new terminologies, new techniques, etc. However, here are many, many more fruitful collaborations with universities, institutes, and industrial partners on all aspects of materials synthesis, characterization and applications that we have (had) over the last years and it would be impossible to name them all.
Could you let us know the main challenges you foresee for the sol- gel process and the sol-gel materials in the next future?
We find that materials are becoming more complex not only in stoichiometry with all the opportunities given by the periodic table (binary, ternary, multinary compounds), but also in structure ranging from highly porous, hierarchical to nanoscale structures, and in addition due to the possible combinations ranging from biology to hybrid and solid state chemistry. With increasing complexity, novel phenomena and new applications are encountered that need to be investigated. Thus, the need for improved experimental but also theoretical approaches is eminent in sol-gel chemistry. In addition, more thorough in-situ investigations of the processes during the formation of the sol particles or the gel network as well as the possibility to get spatially resolved information, e.g. on the location of certain elements or organic moieties in the network require the development of novel characterization techniques.
The sol-gel process is often compared to playing LegoTM. However, I doubt that we – the sol-gel community – are truly able to rationally design complex materials compositions and structures on all length scales and with the endless options given by the periodic table of the elements. Here, much more research and a better understanding are needed and I am really excited by all the progress that we will experience in the future due to these manifold combinations. In addition, the combination of the area of inorganic/organic sol-gel chemistry with the living world (medicine, biology) will definitely be one of the most thrilling topics for the near future.
What is your wish for the sol-gel community ?
Since the first steps in the 1970’s, the sol-gel community is continuously growing and many technological applications rely on products synthesized by sol-gel processing. Since there are almost endless possibilities in what can be done by sol-gel processing, I hope that we will see progress in a variety of interdisciplinary fields with many young researchers becoming interested in the fascinating world of sol-gel processing.
