Dimension-Controlled Dewetting in Hydrophobic Porous Nanocapsules

Water in different physical states has been attracting great interest for decades for its strong association with the origin of life, the biophysical behaviors of biomacromolecules, and the transportation of matter and energy. Structurally well-defined, monodispersed nanocapsules provide excellent opportunities to understand water under confinement. Herein a group of porous and hollow polyoxometalates with varied inner ligands have been studied to investigate the distributions of water inside them in solution states via contrast variation small angle neutron scattering (CV-SANS) techniques. Meanwhile, molecular dynamics simulations have been conducted to cross-examine fitting results of SANS data and provide structural details of the formation of such water distribution patterns. Our work suggests that the densities of water in the core of nanocapsules rely highly on the dimensions of hydrophobic confinement space (cores inside nanocapsules) and can approach the dewetting state at the critical dimension, ca. 1.1 nm.