Synthesis and degradation property of star-shaped polylactide

Abstract

L-lactide(LL) was melt-polymerized;ed by stannous octoate(Sn-oct) with various alcohols such as 1-dodecanol 1,6-hexanediol, glycerol, pentaerythritol(PEr), dipentaerythritol(diPEr), and tripentaerythritol(triPEr) to yield linear or star-shaped poly-L-lactide(PLLA). Star-shaped PLLA would be interesting polymers as the physical properties and degradation rates should be different from those of linear PLLAs. NMR technique was used for the characterization of polymer structure. The numbers of chain arm were evaluated from NMR peak areas of OH groups and methylene groups. Star-shaped structures were obtained when [LL]/[polyol] ratios were over certain value. By the DSC analysis, the starshaped PLLA showed lower T-g and T-m than linear PLLA. As a results of in-vitro degradation, the star-shaped PLLAs showed faster degradation rate than linear PLLAs at 80 degrees C.