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The synthesis of lactic‐acid‐based telechelic prepolymers
Author(s) -
Hiltunen Kari,
Seppälä Jukka V.
Publication year - 1998
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/(sici)1097-4628(19980207)67:6<1011::aid-app7>3.0.co;2-l
Subject(s) - prepolymer , polymer chemistry , crystallinity , gel permeation chromatography , diol , condensation polymer , differential scanning calorimetry , lactic acid , polyester , telechelic polymer , materials science , chemistry , catalysis , organic chemistry , copolymer , polymer , end group , polyurethane , composite material , physics , genetics , biology , bacteria , thermodynamics
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 13 C nuclear magnetic resonance ( 13 C‐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 2 O 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 2 SO 4 also showed high crystallinity; and, according to 13 C‐NMR, they did not contain lactide and D ‐lactic acid structures. © 1998 John Wiley & Sons, Inc. J Appl Polm Sci 67:1011–1016, 1998