Document Type

Article

Publication Date

4-17-2024

Abstract

Natural product-derived materials have gained increasing attention as promising alternatives to petrochemically derived commodity polymers. This shift is driven by the growing awareness of environmental issues and the need for more sustainable and eco-friendly materials. The thiol−ene click reaction to prepare biobased polyols is a strategy to promote the green and environmental protection of polyurethane. Limonene is found in the essential oils of various citrus fruits, particularly in high concentrations in the peels of oranges, lemons, limes, and grapefruits. And geraniol is found in rose oil, citronella oil, and palmarosa oil. The excessive usage of thiol and low conversion of carbon−carbon double bonds (C=C) would severely limit the properties of polyurethane (PU). In this work, a set of limonene and geraniol-based polyols were prepared via the thiol−ene click reaction. I use mercaptoethanol and thioglycerol to produce thiols. Interestingly, the conversion of the C=C was nearly 100% at the limonene and various thiol compounds(-SH) in a stoichiometric ratio without excess of -SH. Then, the prepared polyols were reacted with Cyclohexyl isocyanate (CHDI) and Isophorone diisocyanate (IPDI), Followed by films was cured at 70°C. The structural morphology will be analyzed using Fourier Transform Infrared Spectroscopy (FTIR), while mechanical properties will be assessed through tensile and hardness tests. Thermal characteristics will be studied using thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC). The Tg’s of LM+IPDI, LM+CHDI, GM+IPDI and GM+CHDI were 34.58, 56.49, 75 and 56.49 °C, respectively. The GM+SB+IPDI demonstrated better mechanical properties (Tensile Strength of 18 MPa) than the others due to the higher cross-linking density and complete network.

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