Liquid-liquid phase transition of water in hydrophobic and hydrophilic pores

Effect of confinement on the liquid-liquid transition of water are studied by simulations in the Gibbs ensemble. Upon cooling along the liquid-vapor coexistence curve, confined water undergoes transition from normal to strongly tetrahedral water via a first order phase transition (as in the bulk) or in a continuous way in dependence on pore hydrophilicity. In all cases, transition temperature is only slightly shifted by the confinement. This agrees with the experimentally observed weak effect of confinement on the temperature of the fragile-to-strong transition of water.