We report the working expressions of calculation of local dielectric permittivity ( (r)) under nanoconfinement from dipolar spatial correlations. Three confined geometries are investigated: planar, cylindrical and spherical interfaces. We apply these relations to the calculation of the local components of (r) of water confined in a porous silica framework. Microscopically we highlight that the dielectric profile is correlated to the density of water and hydrogen bonding network.

Nowadays, it is well established that the physical properties of confined liquids strongly differ from those in bulk phase. While dynamical and structural properties were strongly explored, dielectric properties are poorly studied despite their importance in the understanding and the modelling of molecular mechanism in a number of nano-applications such as nanofluidics, nanofiltration, and nanomedicine. Among them, the dielectric permittivity is probably one of the most important. The lack of knowledge about it strongly limits our ability to model fluid-material interactions and more generally our understanding of the behaviour of confined fluids. Recently, the dielectric permittivity of confined water in silica, Metal Organic Frameworks, and graphene materials was found to be slightly higher than the permittivity of water in bulk phase. In this work, the permittivity of water and dichloromethane confined in carbon nanotubes was predicted by means of molecular dynamics simulations. The static dielectric constant was found to be 700, i.e., 10-fold higher than the bulk value. This superpermittivity has, for origin, the excluded volume and the presence of an unconfined direction leading to a pre-orientation of water molecules close to the pore wall and an increase in dipolar fluctuations.

From hydrogen bonds, tert-butanol molecules self-organize in micelle-like supermolecular clusters in the liquid state. While these nanoclusters have been largely investigated in the bulk phase, the confined situation remains seldom. However, from a relevant combination of neutron scattering and molecular simulation, it has been shown that these clusters persisted under hydrophilic cylindrical confinement [