Topology-selective encapsulation of a guest is generally exclusively achieved by a well-defined host. In this article, a macromolecular reverse micelle (PEI@PS), with a hyperbranched polyethylenimine (PEI) as core and polystyrenes (PSs) as shell, is prepared and shown with excellent encapsulation and separation abilities. It is found that the encapsulation and phase transfer is kinetically dependent on the size of the dyes, creating a time window for the separation of dyes. All the experimental results show that the thickness and density of shell plays the most important roles in guest selectivity. In addition, highly size-selective release is also found. This macromolecular reverse micelle (PEI@PS) can find useful applications in the liquid-liquid or solid-liquid extraction separation, especially for the latter. (C) 2013 Wiley Periodicals, Inc.