H. Kitano et al., The structure of water sorbed to polymethoxyethylacrylate film as examinedby FT-IR spectroscopy, J COLL I SC, 242(1), 2001, pp. 133-140
The state of sorbed water and sorbing processes of water to four kinds of v
inyl polymer films were studied by FT-IR. The O-H stretching band of water
sorbed to the films gradually increased on contact with a water vapor of 50
% relative humidity at 25 degreesC and leveled off. The profile of the O-H
stretching band of sorbed water changed with chemical structure of the poly
mers. Water sorbed to poly(methoxyethylacrylate) (PMEA), for example, had a
sharp and large peak at 3625 cm(-1) and a neighboring broader peak with a
long slope in the lower frequency region, which resembled the summation of
the peaks for water sorbed to poly(methylmethacrylate) (PMMA, two sharp pea
ks) and poly(vinylmethylether) (PVME, two broader peaks in the lower freque
ncy region) films. The peak frequencies of the sorbed water were consistent
with the calculated values for water hydrogen-bonded to the model compound
s by using a hybrid density functional method. When water droplets were put
on the polymer film, furthermore, the O-H stretching band of water within
the polymer matrix was obtained using an attenuated total reflection techni
que. An O-H profile similar to that of free water was observed for water in
corporated within the matrix of PMEA and PVME films, whereas those profiles
within the matrix of poly(2-hydroxyethylmethacrylate) (PHEMA) and PMMA fil
ms were largely different from that of free water. This might be in accorda
nce with the difference in biocompatibility of four kinds of polymeric mate
rials. The diffusion coefficients of water vapor in these polymer films wer
e also determined by the time-resolved FTIR method. (C) 2001 Academic Press
.