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Bulk Ring Opening Polymerization of L-Lactide with Calcium methoxide

Authors

  • Marcos Lopes Dias,

    Corresponding author
    1. Instituto de Macromoléculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro, CP. 68525, 21945-970 Rio de Janeiro, RJ Brazil
    • Instituto de Macromoléculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro, CP. 68525, 21945-970 Rio de Janeiro, RJ Brazil.
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  • Luiz Carlos Palermo,

    1. Instituto de Macromoléculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro, CP. 68525, 21945-970 Rio de Janeiro, RJ Brazil
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  • Alexandre C. Silvino

    1. Instituto de Macromoléculas Professora Eloisa Mano, Universidade Federal do Rio de Janeiro, CP. 68525, 21945-970 Rio de Janeiro, RJ Brazil
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Abstract

Summary: Bulk ring opening polymerization (ROP) of L-lactide (LA) initiated by calcium methoxide (Ca(OMe)2) was investigated in LA/Ca molar ratio from 100 to 5000 and reaction times up to 3h at 180 °C. Ca(OMe)2 showed good activity as ROP catalyst, particularly at high catalyst concentration. The polymerization shows a linear relationship between equation imagen and reaction time, typical of a controlled process. The increase of LA/Ca molar ratio decreases the conversion which was maximum (66%) when the polymerization was carried out at 180 °C and LA/Ca = 100. Semicrystalline poly(L-lactic acid) (PLLA) with moderate equation imagen varying from 8,500 to 19,500 and polydispersities from 1.20 to 1.44 were obtained. The increase of LA/Ca molar ratio decreased equation imagen, increased the degree of crystallinity and decreased racemization processes which can be controlled by the polymerization condition. Racemization could be reduced by using low catalyst concentration.

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