We report on novel soluble macromolecules displaying rather peculiar solution behaviour, which allows us to gain full control of their partition into three mutually immiscible liquid media: water, dichloromethane and perfluoro(methylcyclohexane); such polymers may be used as soluble supports for reagents or catalysts, yielding supported species whose solubility preference for one out of three liquid phases can be quantitatively and reversibly switched, thereby simplifying separation considerably.