Anomalous solid-like necking of confined water outflow in hydrophobic nanopores

How do interfaces alter the dynamics of supercooled water?

“…Through a careful series of studies on systems in different sized simulation boxes, we established that in the temperature range 230-270 K, a cubic box with lateral size of 5 nm is sufficient to converge the average dynamical properties in the bulk (see Section S1, S3 and S6 of SI). Length scales corresponding to the size of the dynamical domains observed in bulk are, however, comparable to confinement lengths often observed in biological and technological systems ( 1-2 nm) 57,[85][86][87][88][89][90][91] .…”

“…Length scales corresponding to the size of the dynamical domains observed in bulk are, however, comparable to confinement lengths often observed in biological and technological systems (≳1-2 nm). 57,[85][86][87][88][89][90][91] In order to understand dynamical heterogeneity in supercooled interfacial water we performed a range of simulations on different types of interfaces. Specifically we considered freestanding slabs of thickness between 2 to 5 nm and spherical droplets of diameter between 3 to 10 nm.…”

Electrically Suppressed Outflow of Confined Liquid in Hydrophobic Nanopores

“…A significant ρ HB peak is located in the interface layer for both E = 0 and 0.3 V/nm, which is caused by the densification of water molecules. 40 The higher ρ HB is correlated with the notable surface stress exerted on the confined water, presented in Figure 3e,f. During the outflow, such a peak is reduced by the loss of molecules and vanishes before the failure of the water cylinder, illustrating the H-bond degradation is initiated in the interface layer.…”

“…40 A nominal stress σ and strain ε can be defined as (P in − P) and (ΔV its /V 0 − ΔV/V 0 ), respectively, to characterize the outflow (Figure 1b), where ΔV its is the critical volume change that leads to the complete infiltration of the nanopore. 40 The turning point in the P − ΔV/V 0 curve indicates the breakdown of liquid cohesion and the failure of the confined water cylinder, which corresponds to the ultimate stress in the σ−ε curve. The P − ΔV/V 0 relationship returns to that during the loading process after the breakdown of liquid cohesion, which triggers substantial outflow reflected by the rapid reduction in the number of confined water molecules N w (Figure 1c).…”

“…In addition, our recent work reveals that this liquid outflow is intimately determined by dynamic orientations of molecular dipoles and hydrogenbond networks at the liquid−nanopore interface and can be well described by a solid-like mechanics model with the incorporation of temperature and pore size. 40 Inspired by the response of solid−liquid interaction to electric fields, harnessing the solid-like outflow behavior and the associated metastable state of liquid confinements in an electric field could yield a promising manipulation strategy and control approach to liquid outflow but is currently lacking. In this work, we report an electrical suppression approach to slow the outflow of water confined in hydrophobic nanopores.…”