Isocyanate free condensed tannin-based polyurethanes

• Condensed flavonoid tannin-based polyurethanes were prepared without isocyanates.
• Low temperature-prepared materials have various oligomers structures from tannins.
• Materials heated at 103 °C present more higher molecular weight oligomers.
• Heated materials are results of complex copolymerization between the reagents.
• Coating application was tested and contact angle with water measures were done.

Condensed flavonoid tannins from Maritime Pine (Pinus pinaster), Mimosa (Acacia mearnsii), and Radiata Pine barks, and Quebracho (Schinopsis lorentzii and balansae) wood, were first reacted with dimethyl carbonate. Then hexamethylenediamine was added to these mixtures to form urethane linkages. The resulting materials were analyzed by Fourier transform infrared (FTIR) spectroscopy, matrix assisted laser desorption ionization time of flight (MALDI-TOF) mass spectrometry, gel permeation chromatography (GPC), and thermogravimetric analysis (TGA). Finally the resulting analysis indicated that the products obtained are polyurethanes. Initial wood coating applications tests were carried out under conditions of higher temperature and some pressure, and the contact angle of the surface coatings so prepared was measured.

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