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Catalytic mechanisms of triphenyl bismuth, dibutyltin dilaurate, and their combination in polyurethane‐forming reaction
Author(s) -
Luo ShanGuo,
Tan HuiMin,
Zhang JianGuo,
Wu YiJie,
Pei FengKui,
Meng XiangHong
Publication year - 1997
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(19970808)65:6<1217::aid-app17>3.0.co;2-q
Subject(s) - isocyanate , polyurethane , catalysis , polymer chemistry , chemistry , tetrahydrofuran , curing (chemistry) , materials science , organic chemistry , solvent
The catalytic mechanisms of triphenyl bismuth (TPB), dibutyltin dilaurate (DBTDL) and their combination have been studied in a model polyurethane reaction system consisting of copolyether (tetrahydrofuran–ethyleneoxide) and N‐100; NMR spectroscopy was used to detect the associations between reactants and catalysts. A relatively stable complex was shown to be formed between hydroxyl and isocyanate; the catalysts showed different effects on the isocyanate–hydroxyl complex, therefore resulting in different curing characteristics. The formation of hydrogen bonding between the complexed hydroxyl and other hydroxyl or the resulting urethane provided an “auto‐catalysis” to urethane formation. DBTDL destroyed the isocyanate–hydroxyl complex before catalyzing the reaction through the formation of a ternary complex, whereas TPB was able to activate the isocyanate–hydroxyl complex directly to form urethane. The reaction catalyzed by the combination of TPB and DBTDL gained advantages from the multiple catalytic entities, i.e., TPB, DBTDL, and a TPB–DBTDL complex. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65:1217–1225, 1997