Copolymers of rac-Lactide and -Caprolactone: Conventional Copolymerization vs. Macroinitiator Copolymerization
Polymers and High Performance Materials
Copolymers of rac-lactide (rac-LA) and -caprolactone (CL) were synthesized with tin(II) 2-ethylhexanoate and 1,4-butanediol at 130C using two methods of copolymerization: conventional copolymerization and sequential polymerization using poly(CL) as a macroinitiator for rac-LA. Conventional copolymerizations showed a retarded rate of CL conversion until rac-LA reached high conversion. The macroinitiator method led to reduced overall reaction time to reach high conversion of both monomers. At a low CL comonomer ratio, the copolymers synthesized by the two different methods were very similar but, as the comonomer ratio was increased, differences in monomer sequencing (e.g. random vs. blocky) as determined by 13C-NMR and glass transition were observed. Additionally, macroinitiator synthesis carried out at 150C in an effort to promote transesterification did not show any significant differences from the copolymer synthesized at 130C.
Journal of Macromolecular Science Part A-Pure and Applied Chemistry
Moravek, S. J.,
Storey, R. F.
(2009). Copolymers of rac-Lactide and -Caprolactone: Conventional Copolymerization vs. Macroinitiator Copolymerization. Journal of Macromolecular Science Part A-Pure and Applied Chemistry, 46(4), 339-345.
Available at: http://aquila.usm.edu/fac_pubs/1341