T
wo-dimensional (2D) correlation analysis based on time-resolved FT-IR/attenuated total reflection (ATR)spectroscopy
has been used to study t
he diffusion be
havior of
water and mono- or divalent anions in t
hepositively c
harged membranes of different c
harge density. In 2D FT-IR/ATR spectra, t
he splitting of t
he
water
hars/delta.gif" BORDER=0 >(OH) bending band in t
he spectral range 1700-1500 cm
-1 indicates t
hat t
here are t
hree differentstates of
water in t
he positively c
harged membrane, t
hat is, t
he
water molecules forming strong or
weak
hydrogen bonds
wit
h hydrop
hilic groups of t
he membrane and
water molecularly dispersed
wit
h weaker
hydrogen bonds. T
he
wavenumber difference of t
he
hars/delta.gif" BORDER=0 >(OH) band in t
he lo
w- and
hig
h-c
harge-density membraneindicates t
hat
water molecules form muc
h stronger
hydrogen bonds
wit
h hydrop
hilic groups in t
he
hig
h-c
harge-density membrane. T
he sequential order of t
he t
hree
water bands intensity c
hanges s
ho
ws t
hat, in t
heprocess of
water diffusion into t
he
hig
h-c
harge-density membrane, t
he
hydrogen-bonding interaction bet
ween
hydrop
hilic groups of t
he membrane and
water molecules takes place gradually due to t
he
hig
hly cross-linked net
work structure of t
he membrane; in t
he process of
water diffusion into t
he lo
w-c
harge-densitymembrane, t
he strong
hydrogen-bonding interaction bet
ween
hydrop
hilic groups of t
he membrane and
watermolecules takes place instantaneously and t
his type of
water easily diffuses due to t
he
weak interactionsbet
ween t
he
water molecules and t
he membrane polymer. Furt
hermore, t
he diffusion processes of t
he electrolytesolution suc
h as NaAc and Na
2SO
4 aqueous solutions in t
he positively c
harged membrane
have also beenexamined.