Water, anomalous

The reports were that water condensed from the vapor phase into 10-100-/im quartz or pyrex capillaries had physical properties distinctly different from those of bulk liquid water. Confirmations came from a variety of laboratories around the world (see the August 1971 issue of Journal of Colloid Interface Science), and it was proposed that a new phase of water had been found many called this water polywater rather than the original Deijaguin term, anomalous water. There were confirming theoretical calculations (see Refs. 121, 122) Eventually, however, it was determined that the micro-amoimts of water that could be isolated from small capillaries was always contaminated by salts and other impurities leached from the walls. The nonexistence of anomalous or poly water as a new, pure phase of water was acknowledged in 1974 by Deijaguin and co-workers [123]. There is a mass of fascinating anecdotal history omitted here for lack of space but told very well by Frank [124]. 

Kamb, B. (1971). Hydrogen-bond stereochemistry and "anomalous water." Science 172, 231. 

Many Investigations have been devoted to exploration of the structure of water In aqueous solutions of polymers as well as In water-adsorbed or water-swollen polymeric substances. Although there Is some controversy among researchers regarding the actual structure. It Is generally accepted that water molecules in the vicinity of the polymer segments behave somewhat differently from the normal "bulk" water because of their Interaction with the polymer (l. ) This anomalous water Is often called "bound", "non-freezing", "hydrated", "ordered", and so on. Moreover, some workers have pointed out that there may be present another type of water which is neither identical to the bulk nor to the bound water The amount of these anomalous waters Is apparently... 

For various reasons, almost constant drug release has been observed by some authors and kinetics controlled by the swelling of the polymer have been postulated many times as an explanation. The author [15] has, in fact, proved theoretically that anomalous water transport - a necessary criteria for a non-Fickian solute release - is doubtful with these materials. Let us consider the... 

Quite interestingly, an anomalous water transport was observed for the gels which were the most highly crosslinked with the dialdehydes. Case II transport seemed even to be operating for the 25 mPa s MC gel crosslinked with glyoxal and for the 4000 mPa s MC gel crosslinked with glutaraldehyde. 

R. Kiyono, Y. Asai, Y. Yamada, A. Kishihara and M. Tasaka, Anomalous water transport across cation-exchange membranes under an osmotic pressure difference in mixed aqueous solutions of hydrochloric acid and alkali metallic halide, Seni Gakkaishi, 2000, 56, 298-301 M. Tasaka, T. Okano and T. Fujimoto, Mass transport through charge-mosaic membranes, J. Membrane Sci., 1984,19, 273-288. 

Amphiphilic molecules, when dissolved in organic solvents, are capable of self-assembly to form reversed micelles. The reversed micelles are structurally the reverse of normal micelles in that they have an external shell made up of the hydrocarbon chains of the amphiphilic molecules and the hydrophilic head-groups localized in the interior of the aggregate. Water molecules are readily solubilized in this polar core, forming a so-called water pool. This means that reversed micelles form microcompartments on a nanometer scale. The reversed micelles can host all kinds of substrate molecules whether hydrophilic, hydrophobic, or amphiphilic due to the dynamic structure of the water pool and the interface formed by the surfactant layer, in contrast with a liposome system. The properties of water molecules localized in the interior of reversed micelles are physicochemically different from those of bulk water, the difference becoming progressively smaller as the water content in the micellar system increases [1,2]. The anomalous water at low JVo =[water]/[surfactant] obviously influences the chemical behavior of host molecules in the water pools. 

In 1969, Ellis R. Fippincott (1920-74), at the University of Maryland College Park, performed the first infrared spectroscopic study of "anomalous water," discovered significant differences from the spectra of water, and hypothesized a polymeric form of water he called polywater. Frank J. Donahoe (1922- ), at Wilkes College, warned that if water could spontaneously change to polywater, then "I regard this polymer as... 

Kollman (1944-2001), later famous for studies of proteins, calculated the structure and properties of polymeric water. They relied on claims that the experimentalists were working with a pure substance. Allen and Kollman were limited to computations of only moderate sophistication. Their study, published in 1970, predicted a structure similar to graphite (regular "ice" is similar to diamond). Their calculated energies for polywater and liquid water were quite similar. This begged a question that many chemists had raised earlier If "anomalous water" or polywater forms so readily (and is comparable in energy to liquid water), why had it not been seen before and, for that matter. 

Deryagin and Churayev (1968) reported on a form of water with properties different from those well established for water, and the new form has been referred to as anomalous water. This water has been prepared by Fedyakin (1962) in a sealed glass capillary 2 to 4 jU in diameter and later by Deryagin et al. (1965) by the condensation of water vapor in glass and fused quartz capillaries at relative pressures somewhat less than unity. Among the properties of this water, renamed polywater by Lippincott et al. (1969), are (1) low vapor pressure (2) solidification at — 40°C or lower temperatures to a glass-like state with a substantially lower expansion than that of ordinary water when it freezes and (3) a density of I.OI to I.4g/cm and stability to temperatures of the order of 500°C. 

Polywater (also called anomalous water), which was first described in the 1960s in the Soviet Union and controversially discussed in the 1970s, does not exist, however, and was probably a mixture of colloidal silicic acid. 

In the early 1960s Russian scientists discovered that condensation of water vapor in narrow quartz capillary tubes with diameters less than 100 p,m produced water with anomalous properties the density was 20 or 30% higher than for normal water the freezing point was at least SO"" lower and the boiling point at least 30° higher. Particularly startling was the observation that the vapor pressure was lower than for normal water at the same temperature this implies that the anomalous water is thermodynamically more stable. Hence, with time, all water should be converted to the anomalous form. The unusual properties could, of course, be explained by impurities. Chemical analysis was made very difficult by the fact that less than 100 p,g (10 " g) of the mysterious liquid could be produced in a process which lasted for days. Anyway, no impurities were found. 

After the leader of the Russian research group had given lectures on anomalous water in Britain during the summer of 1966, the experiments were repeated in several British research laboratories with the same results. From Britain the information about and interest in anomalous water spread to the US. Most chemists appear to have been deeply skeptical about the existence of a previously unknown, thermodynamically more stable form of water. On the other hand, if the existence of such a form could be established, it might prove to be the the most important physical-chemical discovery of the century. ... 

In 1969 a group of American spectroscopists published the infrared (IR) and Raman spectra of anomalous water [30]. The observed spectra did not correspond to those of normal H2O molecules. The spectra were therefore interpreted as evidence for the presence of water polymers held together by hydrogen bonds with linear O-H-0 fragments two... 

Thus, a substantial part of bound water in bone tissue is in the weakly associated state characterized by the chemical shift 5h= 1.4-1.7 ppm close to that of individual water molecules in hydro-phobic environment. A mass fraction of this anomalous water is compared with a mass fraction of mineral component. This water is strongly bound in bone tissue, fills very narrow pores, and freezes at r< 250 K. It is moved away from the bones only on strong heating. 

Polyethyleneglycol ethers possess an apparently anomalous water-solubility characteristic in a certain temperature range, their solubility decreases with increasing temperature. 

A high value of c (favorable for high relaxation time of the polymer penetrant system and thus the Deborah number) is observed for materials with low glass transition temperature, namely PVA and PHEMA. This confirms that anomalous water transport is doubtful in water-soluble cellulose derivatives. 

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