The molar mass of 1 (10 kg mol -1 , ~2.5 kg mol -1 per arm) was adjusted by the molar ratio of pentaerythritol : ɛ-CL (1 : 87). As shown by NMR spectroscopy, the following esterification of the hydroxy terminal groups of 1 with compound 2 proceeded quantitatively. The NMR investigations also showed that 1 contained a small number of unreacted hydroxy groups on the pentaerythritol core (≤ 6 % three-arm stars). During esterification with 2, these hydroxy groups are also converted resulting in an average end group functionality of f ≥ 3.8 (conversion p ≥ 95%) in tetra-PCL 3.