Structure modification and crosslinking of methacrylated polylactide oligomers

The effect of molecular architecture on the properties of crosslinked polylactides was studied. D,L-Lactide-based telechelic oligomers with different numbers of arms were functionalized with methacrylic anhydride. Functionalized oligomers were crosslinked with thermal initiation at 90 C, and the mechanical and thermal properties, as well as the gel content, were evaluated. The crosslinking density increased with the number of arms in the oligomers, and the compressive yield strength was built up at the same time. The best mechanical properties (compressive yield strength = 120 MPa, modulus = 2800 MPa, and strain = 5.0%) were obtained with cured polymers prepared with a 100 : 8 ratio of lactide to pentaerythritol. When dimethacrylated butanediol was used as a reactive monomer in curing, polymers with high crosslinking density and mechanical strength were obtained at 37, 60, and 90degreesC. The use of the reactive monomer also enabled high conversions with photoinitiated crosslinking. Finally, hydrolytic degradation and strength retention were demonstrated. (C) 2002 Wiley Periodicals, Inc.