Polymers (Aug 2021)

Blocking and Deblocking of Diisocyanate to Synthesize Polyurethanes

  • Sourita Jana,
  • Debasis Samanta,
  • Mir Muhammad Fahad,
  • Sellamuthu N. Jaisankar,
  • Hongdoo Kim

DOI
https://doi.org/10.3390/polym13172875
Journal volume & issue
Vol. 13, no. 17
p. 2875

Abstract

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Diisocyanates, particularly toluene diisocyanate (TDI), are useful for the preparation of various polyurethanes with specific applications as leather-like materials, adhesives and insoles, etc. Blocking agents can be used for the operational simplicity and to reduce the hazards of TDI. In this paper, we reported the use of 3-(4-bromo-phenyl)-1H-pyrazole to block toluene diisocyanate (TDI). FTIR, NMR, thermogravimetric analysis, contact angle analysis and differential scanning calorimetry (DSC) were used for the characterization. The effectiveness of the blocking was confirmed by spectroscopic techniques. The DSC thermogram showed that blocked adducts deblock at 240 °C, causing the regeneration of TDI, and causing the diisocyanates to react with polyols of different molecular weights, forming polyurethanes. The characterization of the polyurethanes was performed by infrared spectroscopy, nuclear magnetic resonance spectroscopy, thermogravimetric analysis, differential scanning calorimetry and a contact angle study.

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