Low temperature phase properties of water confined in MCM41 mesopores at different hydration levels: A molecular dynamics study

Highlights: • Carried out extensive MD simulation work on water confined in MCM41 mesopores. • Disruption of H-bonding network at 12 wt% hydration leads to liquid-liquid structural transition at 230 K. • As hydration level decreases water molecules tend to attach to pore wall, forming clusters at RT. • As temperature decreases water molecules prefer to attach among themselves. • As hydration level decreases total energy becomes +ve from -ve signifying disruption of H-boning network. Low temperature behavior of water confined in MCM41 mesopores with sub-monolayer of hydration levels has been studied using Molecular Dynamics (MD) simulations. At room temperature, water molecules become more and more attached to the pore surface forming clusters at the pore wall with decrease in the number of water molecules inside the pores. Interestingly, a change in slope in total interaction energy is seen at around 230 K for the lowest hydration level (12 wt%) which is muted out as the hydration level increases. These results indicate that water molecules at the lowest hydration level undergo a first order-like discontinuous structural phase transition at around 230 K.