The hypothesis that the degree of hydration of poly(oxyethylene) (POE) in aqueous solution depends on the mole ratio of water molecules to ether oxygen atoms in the molecule has been verified by studying the isotropic Raman spectra in the O-H stretching region for four short-chain POEs (C 1 E n C 1 with n = 1−4). Excellent coincidence of the O−H stretching Raman band for all four POEs studied in the range of mole ratio H 2 O/O ether from 25 to 0.6 was observed, thus confirming the assumption stated above. A conclusion that all ether oxygen atoms in the POE molecule participate in hydrogen bonding with water molecules has been made.
Excess thermodynamic functions of D 2 O water have been calculated from the vibrationally decoupled O-D stretching spectra of very dilute solutions of HOD in H 2 O. Comparison of the results with reference calorimetric data for water showed a good correspondence for excess heat capacity above the melting point of ice. The excess enthalpy at the melting point also coincides well with latent heat of melting.
Previous studies of OH stretching band of aqueous solutions of short poly(oxyethylene)s POEs showed similarities between ratios R of the intensities of the component around 3200 cnf' (the collective in-phase OH stretching vibrations of hydrogen-bonded aggregates) and the component around 3400 cnf' (the out of phase OH stretches) in dependence on type and concentration of dissolved POEs. According to previous studies on C1EE1 (n = 1 -4) the intensity ratio R is characterized with two minima. We observed the same behavior in the case of C2E2C2. In addition the perfect match of the spectra of C2E2C2 and those of C1EE1 (n = 1 -4) at different concentration showed that the water structure is influenced in a similar way in the cases of C2E2C2 and of C1E11C1.
Applying continuos model, about network of hydrogen bonds, and free energy of water founded by the model, we calculate the concentration of strong hydrogen bonds in liquid normal H20 and heavy D20 water in dependence on temperature in a range of 240K to 400K.
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