Formation of Liquid-condensed mineral phases and the mechanisms of the PILP process: potential for a new morphosynthetic route to nanocomposite materials

• Applicant: Privatdozent Dr. Stephan E. Wolf
• Subject Area: Synthesis and Properties of Functional Materials
• Term: from 2014 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 251939425

This Emmy Noether project is dedicated to the elucidation of the physicochemical mechanisms of the polymer-induced liquid-precursor (PILP) process in particular and the formation of liquid-condensed mineral precursors in general. The PILP process is a bio-inspired synthesis route which allows for the production of mesocrystalline and nanogranular materials at mildest conditions. The genesis of a solid-state material via PILP follows a so-called nonclassical crystallization route which proceeds by accretion of nanodroplets of a liquid-condensed mineral precursor phase. Up to now, the origin of these alleged liquid-liquid phase separation (LLPS) processes was unclear, limiting translation and exploitation of the morphosynthesis potential of PILP processes. We can now demonstrate that LLPS is feasible for a range of inorganic ionic systems: LLPS of inorganic components can occur when sufficiently stable coordination complexes/clusters are formed which then represent a distinct solute species. These clusters act independently from single ions in solution and are the actual demixing species. With this fundamental insight, we can now provide a mechanistical framework of PILP/LLPS processes which rests on established theories. Our results demonstrate that spinodal demixing of inorganic salts is readily achievable for a range of ionic compounds; controlled arrestment of the spinodal demixing gives unparalleled access to a range of morphologies from self-supporting nanoporous networks to nanodroplets castable on substrates. In this continuation, we aim at evolving spinodal decomposition into a morphosynthetic tool which allows for tailored bicontinuous networks of inorganic components with adjustable pore size and curvature. We will further look into the impact inorganic ions have as additives in spinodal decomposition; a special regard will be laid on magnesium which is of central importance for biomineralisation processes.

• DFG Programme: Independent Junior Research Groups
• International Connection: Australia
• Cooperation Partners: Professor Simon Clark, Ph.D.; Professor Dr. Erdmann Spiecker; Professor Dr. Dirk Zahn