Y. Zhang et al., SORPTION AND SWELLING OF BLOCK-COPOLYMERS IN THE PRESENCE OF SUPERCRITICAL-FLUID CARBON-DIOXIDE, The Journal of supercritical fluids, 11(1-2), 1997, pp. 115-134
The sorption and swelling of polystyrene, poly(methyl methacrylate), p
oly(vinyl pyridine) and polyisoprene, and of styrene-methyl methacryla
te, styrene-vinyl pyridine and styrene-isoprene block copolymers, in t
he presence of carbon dioxide, is examined at 35 degrees C and at pres
sures to 1500 psia. Sorption data were obtained using a quartz spring
technique and swelling data were obtained by direct measurement of the
dimensions of a separate sample using a cathetometer. Sorption in the
glassy polymers increases linearly at low pressures before leveling o
ff at higher pressures, while sorption in the rubber polyisoprene is l
inear over the entire range of pressures investigated. Sorption in the
block copolymers shows a continuous transition from the behavior of o
ne homopolymer to the behavior of the other. The Sanchez-Lacombe equat
ion of state is used to model the homopolymer data using the concept o
f order parameters to extend the model to the glassy polymers. A simpl
e linear model based on the homopolymer sorption is adequate to descri
be the copolymer results. (C) 1997 Elsevier Science B.V.