Universal supercritical binary mixture for polymer fractionation

Supercritical fluids are well known for their efficiency to fractionate pol ymers as a function of their molar mass, their architecture and their chemi cal composition, in the case of copolymers. We have used a supercritical so lvent mixture, made of CO, and ethanol, to fractionate poly(ethylene oxide) (PEO) and polystyrene (PS). This mixture which can solubilize both polar ( PEO) and nonpolar (PS) polymers, allows the obtention of a narrow molar mas s distribution with possibility to select the molar mass value and the mola r mass distribution of the extracted sample. The purification of a binary m ixture of star and linear PEO has been also performed.