New polymer syntheses
- Cite this article as:
- Kricheldorf, H.R. & Jonté, J.M. Polymer Bulletin (1983) 9: 276. doi:10.1007/BF00262719
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L-Lactic acid O-carboxyanhydride (L-Lac-OCA) was prepared by phosgenation of L-lactic acid lithium salt. Its polymerization was conducted using a variety of initiators, and the resulting poly(L-lactides) were characterized by 1H-and 13C-NMR spectra, by vapor pressure osmometry (VPO) and by optical rotation. Number average molecular weights > 3 000 were never obtained. Also polymerizations of D,L-Lac-OCA did not give higher Mn's. The formation of isotactic triads was favored under all conditions. Furthermore, copolymerizations of L-Lac-OCA and various α-amino acid N-carboxyanhydrides (NCAs) only yielded low molecular weight poly(depsipeptides). The polymerization mechanism is discussed.