Hydrogen-bonded liquids exhibit a number of extraordinary properties, rendering them very interesting for basic- and application-oriented research. Well known examples are the anomalies of water, in particular, the density anomaly, which is essential for life.
Interfaces strongly affect the properties of liquids. For example, the fluidity of water in nanoscopic confinements depends on the hydroaffinity and size of the environment. The ability to control the behavior of hydrogen-bonded liquids in restricted spaces plays an enormous role for the regulation of biological processes and for the miniaturization in nanotechnology.
Research unit FOR 1583 combined modern techniques of preparation, characterization, and modelling to analyze the interplay of structure, dynamics, and phase behavior of hydrogen-bonded liquids in confinements of different size, hydroaffinity, and softness and for various external conditions, e.g., in a broad temperature range.
In general, the properties of a liquid in a confinement and in the bulk can differ because of the effects of interfaces and of finite size. The former result from specific interactions at the boundary surface, while the latter occur when the size of the confinement is comparable to structural and dynamical length scales of the system. To ascertain the relevance of these effects and to gain a fundamental understanding, mesoporous host materials with functionalized surfaces were prepared in FOR 1583. Moreover, a large number of experimental and theoretical methods were combined to analyze the behaviors of the guest materials. Specifically, the researchers uses methods of scattering, spectroscopy, calorimetry, and microscopy as well as approaches of simulation and modelling. In this way, it was possible to investigate structure and dynamics on a large variety of length- and time scales so as to, on the one hand, obtain fundamental insights into structure-dynamics relations on a microscopic level and, on the other, trace back macroscopic properties to molecular mechanisms.
The investigated confinements covered specially modified surfaces of mesoporous silicates, ion track channels in polymer foils, and droplets of micro-emulsions. The complexity of the enclosed liquids was varied systematically. The used liquids ranged from simple water, water-alcohol, and water-peptide mixtures to complex polymer and protein solutions.