Nucleation-Inspired Materials Chemistry

Contrary to the notion of classical nucleation theory, the occurrence of stable pre-nucleation clusters in aqueous solutions prior nucleation has been demonstrated for various minerals [1]. While it is classically assumed that molecule-by-molecule, atom-by-atom, or ion-by-ion dissolution and growth of un- and metastable nuclei is central to the onset of phase separation, the pre-nucleation cluster pathway is based upon aggregation of larger nanoscopic entities. The process initially yields liquid intermediates, which solidify towards amorphous nanoparticles that eventually transform into crystals. This "non-classical" crystallization pathway has been studied in the most abundant biominerals, calcium carbonate and calcium phosphate, in particular, but it seems to apply for the aqueous formation of many other compounds as well [1].
In this contribution, we introduce the basic notions of phase separation, carving out the difference between classical and so-called non-classical theories. This leads to an overview of the pathway of phase separation via pre-nucleation clusters, highlighting the latest findings in this field. The examples of calcium carbonate [2] and iron(III) oxide [3] show that the non-classical precursors and intermediates can be taken advantage of for the target-oriented generation of materials. This includes a better understanding of the multiple roles of additives, ranging from ions to polymers and biomacromolecules.
 
[1]  D. Gebauer, M. Kellermeier, J.D. Gale, L. Bergström, H. Cölfen, Chem. Soc. Rev. 43 (2014) 2348–2371.
[2]  D. Gebauer, A. Völkel, H. Cölfen, Science 322 (2008) 1819–1822.
[3]  J. Scheck, B. Wu, M. Drechsler, R. Rosenberg, A.E.S. Van Driessche, T.M. Stawski, D. Gebauer, J. Chem. Phys. Lett. (2016) 3123–3130.

Bio: Denis Gebauer obtained his PhD in Physical Chemistry from the University of Potsdam (Germany) in 2008, working at the Max-Planck- Institute of Colloids and Interfaces. After a 2-year postdoctoral stay at Stockholm University (Sweden), he became a research group leader at the University of Konstanz in 2011. His research interests include concepts of nucleation and crystallization as well as biomineralization and materials chemistry in general. He is one of the awardees of the Heinz-Maier-Leibnitz Prizes 2012. Since the beginning of 2013, Denis Gebauer is a Fellow of the Zukunftskolleg of the University of Konstanz.