Materials (Jul 2024)

Self-Healing Thermal-Reversible Low-Temperature Polyurethane Powder Coating Based on Diels–Alder Reaction

  • Katarzyna Pojnar,
  • Barbara Pilch-Pitera,
  • Shahla Ataei,
  • Patrycja Gazdowicz,
  • Beata Mossety-Leszczak,
  • Beata Grabowska,
  • Artur Bobrowski

DOI
https://doi.org/10.3390/ma17143555
Journal volume & issue
Vol. 17, no. 14
p. 3555

Abstract

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This work focused on obtaining a low-temperature powder coating characterized by self-healing properties. To achieve this, acrylic resin, blocked polyisocyanates (bPICs) with 1,2,4-triazole, and unsaturated commercial resin were used. The synthesis of bPICs with triazole enabled the low-temperature curing and reversible Diels–Alder (DA) reaction at 160 °C. The chemical structure of bPICs was confirmed using 1H-NMR. The occurrence of the DA and retro-DA (rDA) reactions in the crosslinked polymer, at temperatures of 60–85 °C and 90–130 °C, respectively, was confirmed using Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA), and FT-IR spectroscopy. The self-healing properties of the powder coating were examined using polarized optical microscopy. Additionally, the occurrence of the DA and rDA reactions between triazole and unsaturated polyester resin was investigated through repeated self-healing tests.

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