Stoichiometric
La
3+, Ce
3+, and Nd
3+ sa
lts of po
ly[(viny
l a
lcoho
l)-
co-(viny
l su
lfate)] (PVAS) copo
lymerpo
lyacids have been studied in aqueous so
lution without added sa
lt. A
ll LnPVAS sa
lts were entire
ly water-so
lub
le in the composition and concentration range investigated. Ratios of the viny
l su
lfate and viny
l a
lcoho
lunits in the copo
lymers were between 1:5 and 1:107,
leading to structura
l charge densities both above andunder the critica
l va
lue needed for counterion condensation of triva
lent counterions. So
lvent activity,
a1, hasbeen measured by the ge
l deswe
lling method in the concentration range of 5 × 10
-4 to 1 × 10
-1 mo
l ofcounterion/kg of water (0.2-9 w/w% of the po
lye
lectro
lyte). Resu
lts are unusua
lly high for po
lye
lectro
lytes(-2 × 10
-6 >
ln
a1 > -3 × 10
-4), and they are comparab
le with va
lues determined in so
lutions of unchargedpo
lymers. Neverthe
less, the different copo
lymers can be c
lear
ly distinguished; the water activity is
loweredin the order of the viny
l su
lfate content of the po
lye
lectro
lytes, except for the one above the critica
l chargedensity. No observab
le difference was caused in the thermodynamic properties by the different
lanthanidecounterions. Reduced osmotic pressure curves and F
lory-Huggins pair interaction parameters have beenca
lcu
lated; both of them were used to estimate degrees of dissociation at zero as we
ll as at finite concentrations.Degrees of dissociation are decreasing with increasing concentration or viny
l su
lfate content of the copo
lymer.They take va
lues between 8-36% at zero po
lymer concentration and they reach zero va
lue simu
ltaneous
lyat ~1 × 10
-3 mo
l of po
lymer chains/kg of water. The average number of re
leased counterions per po
lymerchain (DP
n = 1005) approaches to a
limit of about 4.4 with increasing viny
l su
lfate content. This correspondsto average charge distances of
b 19 nm and charge density parameters of
le.gif"> 0.037. The
latter is, however,a very
low va
lue and indicates a 1/9 contraction compared to the rod-
like assumption.