The synthesis of lactic-acid-based telechelic prepolymers

Kari Hiltunen, Jukka V. Seppälä*

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    14 Citations (Scopus)

    Abstract

    We have studied how different catalysts and diols affect the properties of low-molecular-weight (M w (GPC) <49800 g/mol) lactic-acid-based telechelic prepolymers. The catalysts and diols were tested separately in our previous studies. In this study, we used the best previously tested diols and catalysts together in order to prepare different types of telechelic prepolymers (for example, crystalline or amorphous). All condensation polymerizations were carried out in the melt, using different diols and different catalysts. The prepolymers were characterized by differential scanning calorimetry, gel permeation chromatography, titrimetric methods, and 13C nuclear magnetic resonance ( 13C-NMR). According to NMR, the resulting polymers contained less than 1 mol % of lactic acid monomer and less than 5.1 mol % of lactide. Dibutyltindilaurate, like tin(II)octoate, produced quite good molecular weights, but the resulting prepolymers contained exceptionally high amounts of D-lactic acid structures, and, therefore, these prepolymers were totally amorphous. Antimony(III)oxide produced a high-molecular-weight prepolymer when the diol used was aliphatic. Like DBTL, Sb 2O 3 produced amorphous prepolymers, which contained a lower amount of D-lactic acid structures than DBTL prepolymers. 1,8-dihydroxyanthraquinone produced a different kind of chain structure with Ti(IV)bu and Ti(IV)iso because one prepolymer had high crystallinity, and the other showed only a slight crystallinity. Sulphuric acid produced a very high-molecular-weight prepolymer with aliphatic 2-ethyl-1,3-hexanediol; and with aromatic diols, it produced quite good molecular weights, except with 1,8-dihydroxyanthraquinone. High-molecular-weight prepolymers produced with H 2SO 4 also showed high crystallinity; and, according to 13C-NMR, they did not contain lactide and D-lactic acid structures.

    Original languageEnglish
    Pages (from-to)1011-1016
    Number of pages6
    JournalJournal of Applied Polymer Science
    Volume67
    Issue number6
    DOIs
    Publication statusPublished - 7 Feb 1998
    MoE publication typeA1 Journal article-refereed

    Keywords

    • 13C-NMR
    • biodegradable polymers
    • lactic acid
    • prepolymer

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