This work investigates effects of poly(-butyrolactone) (PBL) with different initiation and termination chain ends on five types of materials properties, including thermal stability, thermal transitions, thermal recyclability, hydrolytic degradation, and dynamic mechanical behavior. Four different chain-end-capped polymers with similar molecular weights, BnO-[C(=O)(CH2)(3)O](n)-R, R = C(=O)Me, C(=O)CH=CH2, C(=O)Ph, and SiMe2CMe3, along with a series of uncapped polymers RO-[C(=O)(CH2)(3)O](n)-H (R = Bn, Ph2CHCH2) with M-n ranging from low (4.95 kg mol(-1)) to high (83.2 kg mol(-1)), have been synthesized. The termination chain end R showed a large effect on polymer decomposition temperature and hydrolytic degradation, relative to H. Overall, for those properties sensitive to the chain ends, chain-end capping renders R-protected linear PBL behaving much like cyclic PBL. (c) 2018 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2018, 56, 2271-2279