Synthesis and properties of high-molecular-weight poly(L-lactic acid) by melt/solid polycondensation under different reaction conditions

Sung Il Moon, Ikuo Taniguchi, Masatoshi Miyamoto, Yoshiharu Kimura, Chan Woo Lee

Research output: Contribution to journalArticlepeer-review

88 Citations (Scopus)

Abstract

The melt/solid polycondensation of L-lactic acid (LA) was successfully conducted using a binary catalyst system comprising tin dichloride hydrate and p-toluenesulfonic acid (TSA). First, a thermal oligocondensate of LA with a degree of polymerization of eight was mixed with the binary catalyst and subjected to melt polycondensation at 180°C for 5 h to obtain a melt polycondensate with an average molecular weight of 13 000 Da. This melt polycondensate was then heat treated at 105°C for 2 h and subjected to solidstate polycondensation under various conditions to obtain a high-molecular weight polymer of poly(L-lactic acid) (PLLA). In a typical case, the solid-state reaction was performed by raising the temperature from 130 to 155°C, or at a constant temperature of 140 or 150°C. In the former case the molecular weight of PLLA increased linearly with the temperature increase, while in the latter case the molecular weight increased above 500 000 Da in a relatively short reaction time. The crystallization of the polycondensate was a key step of this polycondensation and the crystallinity of the PLLA product was well correlated with the increase in the molecular weight. This method can be a direct industrial method for the manufacture of PLLA from LA, which may potentially be an alternative to the currently adopted lactide method.

Original languageEnglish
Pages (from-to)S189-S196
JournalHigh Performance Polymers
Volume13
Issue number2
DOIs
Publication statusPublished - Jun 1 2001
Externally publishedYes

All Science Journal Classification (ASJC) codes

  • Organic Chemistry
  • Polymers and Plastics
  • Materials Chemistry

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