For the living ring-opening polymerization (ROP) of epoxy monomers, the catalytic activity of organic superbases, tert-butylimino-tris(dimethylamino)phosphorane, 1-tert-butyl-2,2,4,4,4-pentakis(dimethylamino)-2?5,4?5-catenadi(phosphazene), 2,8,9-triisobutyl-2,5,8,9-tetraaza-1-phosphabicyclo[3.3.3]undecane, and 1-tert-butyl-4,4,4-tris(dimethylamino)-2,2-bis[tris(dimethylamino)phosphoranylidenamino]-2?5,4?5-catenadi(phosphazene) (t-Bu-P4), was confirmed. Among these superbases, only t-Bu-P4 showed catalytic activity for the ROP of 1,2-butylene oxide (BO) to afford poly(1,2-butylene oxide) (PBO) with predicted molecular weight and narrow molecular weight distribution. The results of the kinetic, post-polymerization experiments, and MALDI-TOF MS measurement revealed that the t-Bu-P4-catalyzed ROP of BO proceeded in a living manner in which the alcohol acted as the initiator. This alcohol/t-Bu-P4 system was applicable to the glycidol derivatives, such as benzyl glycidyl ether (BnGE) and t-butyl glycidyl ether, to afford well-defined protected polyglycidols. The a-functionalized polyethers could be obtained using different functionalized initiators, such as 4-vinylbenzyl alcohol, 5-hexen-1-ol, and 6-azide-1-hexanol. In addition, the well-defined cyclic-PBO and PBnGE were successfully synthesized using the combination of t-Bu-P4-catalyzed ROP and click cyclization. (c) 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012