Low-temperature structure formation and glass transition behaviors oflow-dimensional water

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Static and dynamic properties of the water confined within nano-pores were studied by adiabatic calorimetry and DSC. The internal water within the pores of silica MCM-41 showed its glass transition at 160 K and then 210 K as the pole size increases, while the interfacial water at around 115 K. The 210 K is the glass transition temperature firstly observed and claimed.Inorganic and organic hybrid crystals [Ni(cyclam)(H2O)2]3・24H2O, [Co(H2bim)3](TMA)・0H2O, and [Cr(H2bim)3](TMA)・nH2O have pore diameters 1.0, 1.5, and 1.6 nm, respectively, with the pore wall structure of crystalline framework. No phase transition was observed in the first substance. The water within the nanopores in the latter two shoved its structural ordering and glass transitions, the cooperativeness in the ordering was higher in the Cr compound than in the Co one. While the interfacial water in MCM41 is disordered in any size, the one in these crystals famed the ordered structures conforming to the crystalline framewor … More k of the pore wall.InNa-RUB-18 crystal possessing nano-sheet water between day layers, the water without participating in the hydrogen-bond network showed a phase transition at 194 K and a glass transition at 106K. No anomaly was observed in the hydrogen-bond chain inclding silanol groups.It was found in methanol aqueous solutions within 1.1 nm pores of silica gel that the glass transition behavior in the high concentration region corresponds to that of the systems in which a hydrogen-bond network inherent to pure water is not formed, and that the inherent network is formed in the dilute region and accordingly the glass transition temperature increases rapidly to approach 160K in the pure water. The similar behavior was observed in the ethylene glycol aqueous solutions within MCM41 pores. On the other hand, it was suggested in hydroxylamine solutions that the hydrogen-bond network structure formed by water molecules is not destroyed by introduction of the second component, and a possibility was indicated that a kind of liquid-liquid phase transition occurs.It was concluded that water molecules forms their own characteristic hydrogen-bond network at low temperatures, and that the relaxation time and therefore the glass transition temperature jumps according to the stages of the development in the network. Less