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Study of the frozen water–poly(vinyl alcohol) system by 2 H and 13 C NMR spectroscopy
Author(s) -
Gusev D. G.,
Lozinsky V. I.,
Vainerman E. S.,
Bakhmutov V. I.
Publication year - 1990
Publication title -
magnetic resonance in chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.483
H-Index - 72
eISSN - 1097-458X
pISSN - 0749-1581
DOI - 10.1002/mrc.1260280717
Subject(s) - vinyl alcohol , chemistry , aqueous solution , deuterium , molecule , atmospheric temperature range , melting point , nuclear magnetic resonance spectroscopy , analytical chemistry (journal) , spectroscopy , freezing point , alcohol , crystallography , thermodynamics , organic chemistry , polymer , physics , quantum mechanics
2 H and 13 C NMR techniques were used to investigate the thermodynamic state of water molecules and of poly(vinyl alcohol) (PVA) chain segments in frozen 10% PVA solutions in 99.8% and 8.5% 2 H 2 O in the ‐66 to 3°C temperature range. The minimum amount of water not entering into the structure of ice is shown to correspond to a ratio of three water molecules to four PVA hydroxyl groups. The quantity of unfrozen water in the investigated systems was observed to change in the 5‐6°C range next to the melting point of pure water. The measurements show that, within the same temperature interval, the temperature decrease is accompanied by a sharp decrease in the 2 H spin‐lattice relaxation time T 1 , whereas 13 C T 1 and the width of the 13 C NMR signals increase up until the resolved PVA signals disappear. The correlation time of the motion of water deuterons and the PVA chain segments was calculated from the 2 H and 13 C T 1 data. The interrelation between the data obtained and the cryostructurization processes leading to the formation of gels in frozen aqueous PVA solutions is discussed.