One-pot synthesis and physicochemical properties of high functionality soy polyols and their polyurethane-Urea coatings

• One-pot synthesis of high functionality polyols.
• Characterization of these polyols.
• Synthesis of polyurethane-urea films.
• Evaluation of these films.

This paper explores a new approach for the synthesis of highly functional soy polyol (SP) from soybean oil (SBO). A two-step continuous route has been reported for the development of renewable polyols and their polyurethane/urea (PU-Urea) coatings. The methodology includes epoxidation of oils and subsequent hydroxylation to produce polyols. The SBO and SP were characterized by different spectroscopic techniques such as 1H and 13C nuclear magnetic resonance (NMR) and Fourier transform infrared (FTIR) spectroscopy, Gel permeation chromatography (GPC), Differential scanning calorimetry (DSC) and Thermogravimetric analysis (TGA), and rheological properties were also determined. Through the present approach, we were able to achieve hydroxyl number for SP as high as 231.3 mg KOH/g. Additionally, the relative conversion of epoxide value as 0.001% and iodine value under 1.35 (g of I2 100/g) are superior to the past reports. Different PU-Urea coatings obtained by utilization of the high functionality SP, exhibited excellent thermo-mechanical and solvent resistances. It was found that the molecular design of polyisocyanate and functionality of polyol plays an important role on performance properties of the coatings. The coatings were also evaluated for their in-vitro degradation, contact angle and chemical resistance properties. We observed high glass transition (Tg 171.8 °C), superior cross-linking density of the PU network, chemical resistance and lower degradation rates. The present work can provide an insight on the design and development of high functionality bio-polyols and their PU-Urea coatings.

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