Products Cited in Publications Worldwide Synthesis and Characterization of Novel Urethane Resins Based on Eugenol: A Preliminary Assessment of Their Utility for One-Component, Oxidatively-Curable Coatings

Synthesis and Characterization of Novel Urethane Resins Based on Eugenol: A Preliminary Assessment of Their Utility for One-Component, Oxidatively-Curable Coatings

Chisholm, Bret; Forson, Kelton G; Biswas, Atanu; Cheng, HN

DOI:

Abstract

Three novel, oxidatively curable urethane resins were synthesized using eugenol (EUG), epichlorohydrin, and various di- or tri-isocyanates, resulting in coatings with 69–77 wt% biobased content (assuming epichlorohydrin was the commercial biobased source). These one-component coatings were compared to a commercial long-oil alkyd derived from soybean oil. All experimental coatings exhibited significantly faster drying and curing times than the alkyd benchmark. Mechanical and chemical resistance properties varied depending on the isocyanate used and the molecular characteristics of the resins. During the initial 20-day ambient curing period, the alkyd coating demonstrated steadily increasing chemical resistance and uniform wear during the solvent rub testing used to assess solvent resistance. In contrast, the EUG-based coatings exhibited lower early-stage chemical resistance, with failure mechanisms involving microcracking and gel particle formation. This was attributed to their low molecular weight and compact, globular structures, which limited polymer entanglement and favored intramolecular oxidative crosslinking, leading to heterogeneous network formation. After extended curing (148 days), two of the EUG-based coatings achieved chemical resistance comparable to the alkyd and demonstrated over threefold increases in hardness, but with reduced reverse impact strength resistance. The third resin, having the lowest molecular weight and highest glass transition temperature, produced a coating with the highest hardness but the poorest resistance to solvent and impact stress, likely due to extensive microcracking. These results confirm the potential of eugenol-based urethanes for sustainable coatings, with performance highly dependent on molecular design—highlighting the critical role of molecular architecture in tailoring long-term durability and mechanical properties.

Keywords

Eugenol ; Urethanes ; Biobased resins ; Oxidatively curable coatings ; Alkyds

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Tris(6-isocyanatohexyl)isocyanurate

A13103583779-63-395% (T)

Tris(6-isocyanatohexyl)isocyanurate

384.0/500g

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