Synthesis of poly(L-lactic acid) with improved thermal stability by sulfonic acid-catalyzed melt/solid polycondensation.
writer：Bo Peng, Yutao Xu, Jijiang Hu, Zhiyang Bu, Linbo Wu*, Bo-Geng Li.
keywords：Biodegradable polymers, Biobased polymers, Poly(L-lactic acid), Polycondensation, Thermal stability, Nonmetallic catalyst
source：期刊
specific source：Polymer Degradation & Stability, 98 (2013), 1784-1789
Issue time：2013年
Melt/solid polycondensation (MP/SSP) is deemed as an alternative synthetic route besides ring-opening polymerization (ROP) in synthesizing poly(L-lactic acid) (PLLA). However, it is found that PLLA synthesized by MP/SSP has much poorer thermal stability than that by ROP due to more residual Sn(II) metallic catalyst in the former, but sulfonic acids does not show any detrimental effect on the thermal stability of PLLA. To synthesizing PLLA with good thermal stability by MP/SSP, a variety of commercially available sulfonic acids were screened as catalysts in MP/SSP of PLLA. Among these nonmetallic catalysts, it was found that 1,3-propanedisulfonic acid (PSA) and 1,5-naphthalene disulfonic acid (NSA) exhibited satisfactory
catalytic reactivity and PLLAs with excellent thermal stability, high molecular weight, little
coloration and good optical purity were successfully synthesized by MP/SSP. The decomposition temperature was increased by 80e100 C in comparison to SnCl2-catalyzed PLLA, and the thermal stability is comparable to commercial PLLA produced by ROP.