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Magnetization‐prepared NMR imaging of water penetration into poly(vinyl alcohol)–poly( N ‐vinyl‐2‐pyrrolidone) hydrogels
Author(s) -
Strounina Ekaterina V,
Hill David JT,
Whittaker Andrew K
Publication year - 2010
Publication title -
polymer international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.592
H-Index - 105
eISSN - 1097-0126
pISSN - 0959-8103
DOI - 10.1002/pi.2860
Subject(s) - vinyl alcohol , self healing hydrogels , 2 pyrrolidone , polymer , aqueous solution , polymer chemistry , materials science , penetration (warfare) , chemical engineering , diffusion , chemistry , organic chemistry , composite material , thermodynamics , physics , operations research , engineering
Abstract Poly(vinyl alcohol)–poly( N ‐vinyl‐2‐pyrrolidone) (PVA–PVP) polymer network hydrogels were prepared by subjecting an aqueous solution of PVA–PVP to gamma irradiation. The hydrogels had initial water contents of approximately 87%, and upon further immersion in water the hydrogels absorbed significantly more, reaching a final water content of about 95%. The use of magnetization‐prepared NMR imaging enabled acquisition of T 2 ‐weighted NMR images from which T 2 maps were constructed and subsequently instantaneous concentration profiles of water molecules were determined. The concentration profiles could be described using Fick's second law of diffusion and the resultant diffusion coefficients were in excellent agreement with those determined from mass‐uptake measurements reported previously. In addition an apparent change in water content over longer times was observed from the NMR images. This phenomenon could be attributed to changes in the distribution of T 2 relaxation times due to rearrangement of the water molecules, or alternatively diffusion of non‐crosslinked polymer chains out of the hydrogel network. Copyright © 2010 Society of Chemical Industry