Summary: Spirocyclic initiators were prepared by condensation of Ge(OEt)4 and tetra(ethylene glycol), TEG, or PEG‐2000 ( = 2 000 Da). These spirocycles were used as initiators for the ring‐expansion polymerization of L ‐lactide in chlorobenzene at 120 °C. The resulting cyclic block copolymers were reacted in situ with aliphatic dicarboxylic acid dichlorides (ADADs) or with hexamethylene diisocyanate (HMDI) to achieve chain extension. The reaction conditions were optimized via model reactions. The isolated Ge‐free multiblock copolymers were characterized by viscosity and by 1H NMR measurements. In selected cases SEC measurements and MALDI‐TOF mass spectrometry were conducted. The mass spectra revealed small amounts of cyclic oligo‐ and polylactides, whereas the high molecular weight multiblock copolymers did not “fly”.
