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NMR characterization of absorbed water in equilibrium swollen hydrogel P(AM‐NaA)
Author(s) -
Li Baohui,
Ding Datong,
Wang Yig,
Sun Pingchuan,
Ma Jianbiao,
He Binglin
Publication year - 1999
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19990531)72:9<1203::aid-app9>3.0.co;2-r
Subject(s) - bound water , relaxation (psychology) , acrylamide , free water , swelling , polymer chemistry , characterization (materials science) , chemistry , materials science , polymer , monomer , molecule , organic chemistry , composite material , nanotechnology , psychology , social psychology , environmental engineering , engineering
The behavior of absorbed water in equilibrium‐swollen poly(acrylamide‐ co ‐sodium acrylate) [P(Am‐NaA)] hydrogel is studied with 1 H nuclear magnetic resonance ( 1 H‐NMR). The observed non‐exponential decay of the spin–spin relaxation data manifests at least two distinguishable environmental states of the absorbed water in all samples. The component, characterized by the relatively shorter T 2 , is associated with the more tightly bound water; whereas the other, characterized by longer T 2 , might be a combination of near normal and loosely bound water. Attention is directed to the way in which relaxation times and the corresponding fraction of each type of water behave as a function of the crosslink density at 25°C. There is evidence of a sudden change of the crosslink state in P(Am‐NaA) hydrogel at crosslink density of about 1.0%. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 72: 1203–1207, 1999