Lactic acid based poly(ester-urethanes): Use of hydroxyl terminated prepolymer in urethane synthesis

Kari Hiltunen*, Jukka V. Seppälä, Mika Härkönen

*Corresponding author for this work

    Research output: Contribution to journalArticleScientificpeer-review

    96 Citations (Scopus)


    We studied a two step process for lactic acid polymerization: in the first step, the lactic acid is condensation polymerized to a low molecular weight hydroxyl terminated prepolymer and then the molecular weight is raised by joining prepolymer chains together using diisoryanate as the chain extender. The resulting polymer is a thermoplastic poly (ester-urethane). The polymer samples were carefully characterized with 13C-NMR, GPC, DSC, and IR. The results indicate that high conversions of lactic acid can be achieved, as well as independent control of the stereostructure, long chain branches, molecular weight average, and molecular weight distribution. Lactic acid is converted into a poly(ester-urethane) with a weight average molecular weight as high as 390.000 g/mol and a glass transition temperature of 53.7°C. The analyzed content of the monomer in the prepolymer is less than 1 mol % and the lactide content 2.4 mol %, while the final poly(ester-urethane) is essentially monomer and lactide free. The mechanical properties of the poly (ester-urethane) are comparable to those of polylactides.

    Original languageEnglish
    Pages (from-to)1091-1100
    Number of pages10
    JournalJournal of Applied Polymer Science
    Issue number8
    Publication statusPublished - 22 Feb 1997
    MoE publication typeA1 Journal article-refereed


    • C13-NMR
    • DSC
    • GPC
    • IR
    • lactic acid
    • poly(ester urethane)
    • prepolymer


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