FRACTIONATION OF POLY(ETHYLENE OXIDE) STAR SAMPLES BY SUPERCRITICAL FLUIDS

Supercritical fluids have been used for the fractionation of poly(ethy lene oxide), Indeed, supercritical fluids are well known for their eff iciency in the fractionation of polymers. Polymer fractions of similar or lower molar mass distribution can be isolated with higher purity a nd lower energy costs than with other fractionation methods. The fract ionation of poly(ethylene oxide) (POE) is reported at 423 K in the pre ssure range 8-35 MPa. Used as supercritical fluid HCFC 142b (1-chloro- 1,1-difluoroethane, CH3CCIF2) was found to be quite efficient yielding polymers with a very narrow molar distribution. These results enable tochose the optimum pressure conditions for molecular architecture fra ctionation. The fractionation of a binary mixture of star and linear c hains of poly(ethylene oxide) has been studied. The separation of line ar chains and star structure appears to be very efficient for a short elution time.