Polymer, Vol.36, No.15, 2947-2956, 1995
Novel Star-Shaped Polylactide with Glycerol Using Stannous Octoate or Tetraphenyl Tin as Catalyst .1. Synthesis, Characterization and Study of Their Biodegradability
Novel star-shaped polyesters were synthesized by reacting L-lactide (LLA) with glycerol (GL) in the presence of stannous octoate or tetraphenyltin as catalyst. These polymers were characterized by nuclear magnetic resonance, Fourier-transform infra-red spectroscopy, differential scanning calorimetry (d.s.c.) and thermogravimetric analysis. D.s.c. curves showed that these polymers are semicrystalline when the ratio LLA/GL is higher than 20/1 (mol/mol). When this molar ratio falls below 20/1, the polymers are amorphous. The molecular-weight distribution of these polymers was studied with gel permeation chromatography measurements, which showed that the M(n) decreased proportionally to the glycerol content in the polymer. The potential biodegradability of these polymers was assessed with the aid of enzymatic and alkali hydrolysis.
Keywords:MASSIVE POLY(ALPHA-HYDROXY ACIDS);STRUCTURE-PROPERTY RELATIONSHIPS;BLOCK-COPOLYMERS;POLY(ETHYLENE GLYCOL);EPSILON-CAPROLACTONE;AQUEOUS-MEDIA;SOFT SEGMENT;DEGRADATION;LACTIDE;POLYMERIZATION