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New Attempt at the Stereoselective Polymerization of Lactide by Using Crystallization during Polymerization

✍ Scribed by Akihiro Ando; Kunio Kimura; Yuko Onda; Yuhiko Yamashita

Publisher
John Wiley and Sons
Year
2005
Tongue
English
Weight
147 KB
Volume
26
Category
Article
ISSN
1022-1336

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✦ Synopsis

Abstract

Summary: The stereoselective polymerization of partial rac‐lactide was attempted by using crystallization during polymerization. Polymerizations were carried out with trifluoromethanesulfonic acid in a mixed solvent of toluene and octane. The molar content of L‐lactate in the feed was 95%. Polymerization proceeded with the elimination of D‐lactate by means of crystallization. Poly(L‐lactic acid) (PLLA) crystals were first precipitated and then plate‐like poly(lactic acid) (PLA) crystals were finally obtained, of which the composition of L‐lactate was 97.6% and the $\overline M _{\rm n}$ was 1.68 × 10^4^.

The polymerization time dependence of the microstructure of poly(lactic acid), i.e., the percentage of mm triads (mm%), prepared from partial rac‐lactide in toluene‐70.

imageThe polymerization time dependence of the microstructure of poly(lactic acid), i.e., the percentage of mm triads (mm%), prepared from partial rac‐lactide in toluene‐70.

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Kinetics of Bz202-initiated polymerization of VAC in pyridine at 60 ° were investigated. The polymerization was significantly retarded by pyridine. The monomer exponent decreased from 2.5 at a relatively low [Bz2Oz] (1.0 x 10 -2 M) to 2.0 at [Bz202] /> 4.0 x 10 -2 M. The observed kinetic features we