In this study, various organic compounds, with different activation modes, have been tested as catalysts for the ring-opening polymerization (ROP) of cyclic butylene terephthalate oligomers (CBT) in bulk at 210 degrees C, using tertbutylbenzyl alcohol (tBnOH) as initiator. Among them, 1,3,5-triazabicyclo [4.4.0] dec-5-ene (TBD) appeared to be the most efficient, achieving high monomer conversions in short reaction times (within minutes). Analysis by size-exclusion chromatography (SEC) of the poly(butylene terephthalate) (PBT) synthesized using this catalyst also showed that the polymerization follows the expected theoretical M-n trend for molecular weights up to 50 kg center dot mol(-1). Chain-end fidelity relatively to the alcohol initiator has been confirmed by MALDI-TOF mass spectroscopy, which showed that all polymer chains possess the tert-butylbenzyl moiety as chain-end. Finally, to demonstrate the potential of this system for the synthesis of PBT-based block copolymers, a monomethyl ether poly(ethylene glycol) (PEG) of 5000 g center dot mol(-1) has been employed as initiator for the ROP of CBT. A PEO-b-PBT block copolymer of 15,000 g center dot mol(-1) could thus been obtained, as confirmed by the shift of the SEC traces towards higher molecular weights and the same diffusion coefficient determined for H-1 NMR signals of the PEO block and the PBT block. (C) 2017 Wiley Periodicals, Inc.