In this article, we provide a concept of a two-phase polymerization system consisting of immiscible monomer and room temperature ionic liquid (IL). The catalyst is immobilized in the IL phase where polymerization takes place. The produced polymer is extracted by the monomer, and the remaining IL phase is catalytically active for more polymerizations. Thus, common volatile organic solvents are no longer needed. Ring-opening polymerization of cyclohexene oxide (CHO) in 1-n-butyl-3-methylimidazolium tetrafluoroborate IL ([bmim][BF4]) using scandium triflate [Sc(OTf)3] catalyst serves as a realistic example of such concept. The yield of polyCHO in [bmim][BF4] is higher than that in bulk. IL containing Sc(OTf)3 can be used for at least three times. A circulatory polymerization process is carried out with added catalyst to keep a relatively high yield in following circulation processes. The assignments of proton signals of polyCHO in 1H NMR are discussed in detail. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012