Lecture: Bio-Inspired Organic-Inorganic Hybrid Materials 

Lecturer: Prof. Helmut C？lfen, Department of Chemistry, University of Konstanz, Germany 

Time: 9:30 am, Oct 8, 2015 

Location: Meeting Room 205 of Administration Building 

Introduction of Lecturer: 

Helmut C？lfen is full professor for physical chemistry at the University of Konstanz. He started in Konstanz in 2010 after having worked for 16 years at the Max-Planck-Institute of Colloids and Interfaces in Potsdam and having rejected a call for a chair in physical chemistry at the university of Duisburg-Essen and a chair for materials chemistry at the university of Stuttgart. His research interests are in the area of nucleation, classical and non-classical crystallization, Biomineralization, synthesis of functional polymers, directed self assembly of nanoparticles and fractionating methods of polymer and nanoparticle analysis – especially Analytical Ultracentrifugation. His group has made contributions to high resolution particle size analysis with Angstr？m resolution in solution, Mesocrystals, Nonclassical Crystallization, CaCO₃ crystallization and additive controlled crystallization. Also, Prenucleation Clusters were identified as stable species even in undersaturated CaCO₃ solution opening an alternative crystallization pathway for CaCO₃ via the aggregation of the prenucleation clusters. He has published about 260 research papers, reviews and book chapters as well as a textbook on Mesocrystals and Nonclassical Crystallization. He serves on the editorial / advisory boards for Bioinspired Materials, Current Nanoscience, Crystals, Crystal Engineering Communications, Journal of Biomaterials and Nanobiotechnology, Journal of Materials Chemistry B, Inorganics, Macromolecular Bioscience, Nanomaterials, Particle & Particle Systems Characterization and The Scientific World Journal, is Editor in chief of Crystals, Co-editor of Current Nanoscience and is member of the German Chemical Society and fellow of the Royal Society of Chemistry. He received several awards including the Hermann Schnell price of the German Chemical Society for the best young researchers in macromolecular science and the Academy award of the Berlin Brandenburg Academy of Science and Humanities. He has been listed in the Thomson Reuters list of top 100 chemists worldwide for the years 2000-2010. 

Lecture Abstract: 

Biominerals teach excellent lessons about advanced materials design. Their structural design is optimized for the specific materials purpose and often, the beneficial properties are generated on several hierarchy levels. Consequently, Biominerals are an intense subject of research to reveal the design principles. This led to the discovery of amorphous or even liquid precursors to single crystals in Biomineralization and additive controlled crystallization events. Non classical particle mediated crystallization pathways were found to be important besides the classical crystallization path.  

This presentation begins with self-assembled hierarchical layered materials from anisotropic nanoparticles aligned by modified self-assembling polyoxazoline polymers with mesogens forming liquid crystals as driving force towards crystallization. Furthermore, an attempt towards combination of several advantageous biomineral properties, namely the fracture resistance of Nacre, the wear resistance of chiton teeth and the magnetic properties of magnetotactic bacteria will be reported. The third example is bio-inspired elastic cement synthesized via a non-classical crystallization pathway. Calcium-silicate-hydrate (C-S-H) nanoparticles, the glue in concrete, are stabilized by copolymers with anionic groups and moieties able to form hydrogen bonds. These polymers bind to C-S-H nanoparticles at pH 12 and stabilize them. Further pH increase leads to destabilization and subsequent nanoparticle aggregation in crystallographic register forming a mesocrystal with a similar structure to a sea urchin spine. This mesocrystal is elastic and can be bent without breaking. This is a further demonstration that bio-inspired synthesis and structuration of organic-inorganic hybrid materials can lead to significant materials improvement – even for the most used synthetic material.