HIGH-RESOLUTION C-13 AND H-1 SOLUTION NMR-STUDY OF POLY(LACTIDE)

High-resolution 500 MHz solution-state H-1 and C-13 NMR spectra of var ious poly(lactides) indicate at least hexad stereosequence sensitivity . The poly(lactides) were prepared in vials by melt polymerization of various combinations of L-lactide, D-lactide, and meso-lactide at 180 degrees C for 3 h using tin(II) bis(2-ethylhexanoate) (tin(II) octoate ) as the catalyst in a 1:10 000 ratio. The intensity distribution of t he various stereosequence resonances in the NMR spectra indicates a pr eference for syndiotactic addition during the polymerization process. Minimal evidence of transesterification was observed for these polymer ization conditions.