Amorphous water

Amorphous water (also called glassy water or amorphous ice) can form when the temperature is decreased extremely rapidly below the glass transition temperature (Tg) of water (about 130 K at 0.1 MPa) (Mishima and Stanley, 1998). There are three types of amorphous ice low-density amorphous ice (LDA), high-density amorphous ice (HDA), and very high-density amorphous ice (VHDA), with VHDA being discovered most recently (Finney et al., 2002). 

J Pitha, J Pitha. Amorphous water-soluble derivatives of cyclodextrins. Nontoxic dissolution-enhancing excipients. J Pharm Sci 74 987-990, 1985. 

In conclusion, decrease in cyclohexanone oxime yield and caprolactam selectivity with time on stream is a major factor in the use of boria on alumina catalyst in the rearrangement reaction. Coke deposition and basic by-product adsorption have been suggested as a means of deactivation. In addition the conversion of water soluble boron, which is selective to lactam formation, to an amorphous water insoluble boron species is another factor that can account for the catalyst deactivation. 

The diagram of ice Ih has a distinct peak at r = 520 pm, which does not occur in liquid water. At 77 K, the g(r) vs r diagrams of amorphous water solid and liquid water are very similar to each other. 

A patent application [25] was filed on March 13, 1956 on the catalytic cracking of hydrocarbons with hydrogen X in the names of Milton and Breck. This application, too, was rejected by the examiner because he could not understand wherein our crystalline zeolite X was different from the amorphous, water softening zeolites of the prior art. This objection should have been easily overcome as it was in the basic A and X cases. For some unknown and still unexplained reason, however, this application was abandoned by our patent department on June 30, 1959. 

Brovchenko I, Oleinikova A. Four phases of amorphous water simulations versus experiment. 1. Chem. Phys. 2006 124 164505. Kumar R, Schmidt IR, Skinner IL. Hydrogen bonding definitions and dynamics in liquid water. 1. Chem. Phys. 2007 126 204107. Geiger A, StiUinger FH, Rahman A. Aspects of the percolation process for hydrogen-bond networks in water. 1. Chem. Phys. 1979 70 4185-4193. 

Irie, T. Eukunaga, K. Yoshida, A. Uekama, K. Pales, H.M. Pitha, J. Amorphous water-soluble cyclodextrin derivatives 2-hydroxyethyl, 3-hydroxypropyl, 2-hydroxyisobu-tyl, and carboxamidomethyl derivatives of (3-cyclodextrin. Pharm. Res. 1988, 5 (11), 713-717. 

Therefore, experiments are performed on immobilized liquids , or in other words on amorphous water (also called vitreous water or glassy water). Currently, three structurally distinct amorphous states of water are known low- (LDA) , high- (HDA) and very high- (VHDA) density amorphous ice We emphasize that HDA is not a well defined state but rather comprises a number of substates. It has been suggested to use the nomenclature uHDA ( unrelaxed HDA ) ", eHDA ( expanded HDA ) " and/or rHDA ( relaxed HDA ) to account for this. Even though no signs of micro-crystallinity have been found in neutron or X-ray diffraction studies, it is unclear whether... 

Herein, we expand on the discussion of our recently observed isothermal amorphous-amorphous-amorphous transition sequence. We achieved to compress LDA in an isothermal, dilatometric experiment at 125 K in a stepwise fashion via HDA to VHDA. However, we can not distinguish if this stepwise process is a kinetically controlled continuous process or if both steps are true phase transitions (of first or higher order). We want to emphasize that the main focus here is to investigate transitions between different amorphous states at elevated pressures rather than the annealing effects observed at 1 bar. The vast majority of computational studies shows qualitatively similar features in the metastable phase diagram of amorphous water (cf. e.g. Fig.l in ref. 39) at elevated pressures the thermodynamic equilibrium line between HDA and LDA can be reversibly crossed, whereas by heating at 1 bar the spinodal is irreversibly crossed. These two fundamentally different mechanisms need to be scrutinized separately. 

Properties Amorphous, water dry matter mass ratio 0.16, specific surface area... 

Polymer I was an amorphous water-soluble polymer with an inherent viscosity of 0.33 and a Tg of 26°C. The Mn and were 6,419 and 15,546 respectively. The ionic polyester displayed excellent adhesive properties as shown in Figure 1. Absolute peel force values could not be obtained... 

---