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Polylactones, 67
Author(s) -
Kricheldorf Hans R.,
Rost Simon
Publication year - 2004
Publication title -
macromolecular chemistry and physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.57
H-Index - 112
eISSN - 1521-3935
pISSN - 1022-1352
DOI - 10.1002/macp.200400027
Subject(s) - polymer chemistry , copolymer , chlorobenzene , chemistry , ethylene glycol , polymerization , ring opening polymerization , inherent viscosity , proton nmr , condensation polymer , intrinsic viscosity , organic chemistry , polymer , catalysis
Summary: Spirocyclic initiators were prepared by condensation of Ge(OEt) 4 and tetra(ethylene glycol), TEG, or PEG‐2000 ( $\overline M _{\rm n}$ = 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 1 H 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”.Structure of spirocyclic Ge‐initiator used here.