Evidence of Spontaneous Formation of Nanoporous Ices Assisted by Polymer Arrays

Nanoporous ices, also referred to as water oxygen-lattice frameworks (WOFs) due to their structural characteristics, exhibit promising potential for applications in gas storage, purification, and separation owing to their high surface-to-volume ratio. This prospect has attracted significant interest from both experimental and computational researchers. To identify nanoporous ice structures with small pores, we conducted a comprehensive computational search using molecular dynamics simulations at 270 K, employing polymers as structural templates. Notably, by systematically varying the unit-cell angle γ and the spacings between polymers, we observed the spontaneous formation of ∼40 novel WOFs. Furthermore, our analysis revealed that the liquid-to-WOF phase transitions are the first-order phase transitions, with freezing temperatures near ambient conditions under atmospheric pressure. A key finding is that successful WOF formation requires interpolymer spacings between 5.0 and 10.0 Å, which accommodate confined water as a monolayer, bilayer, or trilayer. Overall, this work demonstrates the effectiveness of the host-guest approach in fabricating WOFs and underscores their rich phase behavior. These novel nanoporous ice frameworks hold considerable promise for future technological applications.