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Equilibrium properties and kinetics of self-assembly of anisotropic colloids and molecular liquids

Final Report Summary - ANISOKINEQ (Equilibrium properties and kinetics of self-assembly of anisotropic colloids and molecular liquids)

The proposed research project aims to study the properties of new materials made of anisotropic colloids as building blocks, to characterize the anomalies of doubly metastable water, both supercooled and at negative pressure, and to unravel the mechanism of ice nucleation (from supercooled liquid water) and of bubble nucleation (from liquid water at negative pressure).

The last few decades have seen a huge growth in the research on novel soft materials to be exploited in nanotechnology, and an efficient route to build them is to make use of self-assembly. The term self-assembly refers to the reversible and cooperative assembly of predefined components into an ordered super- structure. Self-assembly is responsible for nanostructure formation in colloidal, amphiphilic, polymeric, and biomolecular materials.
However, unlike most of the work of the last decade on particle self-assembly, which has focused on colloidal systems of spherically-shaped particles with isotropic interactions, not enough effort has been put yet into understanding and controlling the self-assembly mechanism in suspensions of irregularly shaped or/and anisotropically interacting colloidal particles (the latter also called "patchy colloids").
Patchy colloids have been recently used to reproduce the colloidal analogue of a vitally important molecule: water.
Water is the only known non-metallic substance that expands when freezing.
Understanding the anomalies of supercooled liquid water and the mechanism of ice nucleation still remains an open and challenging question and it is of fundamental interest to many scientific disciplines, ranging from meteorology to food science and biology.
However, on the one side length and time scale relevant for water crystallisation are unattainable with up-to-date experimental techniques.
On the other side, computer simulations of ice crystallisation have been a great challenge, the difficulty been that hydrogen bonding between individual water molecules yields a disordered three-dimensional hydrogen-bond network that hinder ice formation.
Metastable liquid water presents anomalies when supercooled and brought at negative pressures: at these thermodynamic conditions water tends to phase transform into vapor. Therefore, the project will also tackle the study of bubble nucleation from over-stretched metastable liquid water.