Star polymer 3 was synthesized according to Scheme 2a in two steps as previously reported. At first, 1 was synthesized by ROMP of ɛ-CL using pentaerythritol as starter and Sn(oct)2 as catalyst. The molar ratio of ɛ-CL : pentaerythriol : Sn(oct)2 was adjusted to 87 : 1 : 0.1. Subsequently, the hydroxy terminal groups of 1 were converted with compound 2 to yield 3.