Multiblock copolymers of L-lactide and trimethylene carbonate.
Sequential copolymerizations of trimethylene carbonate (TMC) and l-lactide (LLA) were performed with 2,2-dibutyl-2-stanna-1,3-oxepane as a bifunctional cyclic initiator. The block lengths were varied via the monomer/initiator and via the TMC/l-lactide ratio. The cyclic triblock copolymers were transformed in situ into multiblock copolymers by ring-opening polycondensation with sebacoyl chloride. The chemical compositions of the block copolymers were determined from (1)H NMR spectra. The formation of multiblock structures and the absence of transesterification were proven by (13)C NMR spectroscopy. Differential scanning calorimetry (DSC), wide-angle X-ray scattering (WAXS), and dynamic mechanical analysis (DMA) measurements confirmed the existence of a microphase-separated structure in the multiblock copolymers consisting of a crystalline phase of poly(LLA) blocks and an amorphous phase formed by the poly(TMC) blocks. Stress-strain measurements showed the elastomeric character of these biodegradable multiblock copolymers, particularly in copolymers having epsilon-caprolactone as comonomer in the poly(TMC) blocks.
Pospiech
Doris
D
Institut für Technische und Makromolekulare Chemie, Bundesstrasse 45, D-20146 Hamburg, Germany. kricheld@uni-hamburg.de
Komber
Hartmut
H
Jehnichen
Dieter
D
Häussler
Liane
L
Eckstein
Kathrin
K
Scheibner
Holger
H
Janke
Andreas
A
Kricheldorf
Hans R
HR
Petermann
Oliver
O
D002152:Calorimetry, Differential Scanning; D004146:Dioxanes / Q000138:chemical synthesis* / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D015394:Molecular Structure; D011091:Polyesters / Q000138:chemical synthesis* / Q000737:chemistry; D012542:Scattering, Radiation; D013696:Temperature; D014965:X-Rays
D004146:Dioxanes; D011091:Polyesters; C443643:trimethylene carbonate; C033616:poly(lactide)