Facile synthesis of a castor oil‐based hyperbranched acrylate oligomer and its application in UV‐curable coatings

Abstract Fabrication and performance of the castor oil (CO)‐based hyperbranched acrylate (C20AA) UV‐curable coatings are highlighted in this work. Herein, C20AA was obtained through a facile reaction of a castor oil‐based hyperbranched polyol (C20) with acrylic acid. FT‐IR and 1 H NMR spectra confirmed the synthesis of the target C20AA. Subsequently, the as‐prepared C20AA was employed for crosslinking a commercialized linear polyurethane acrylate (PUA) UV‐curable oligomer. Specifically, by varying the content of C20AA over the range of 0, 20, 40, and 60 wt%, a series of UV‐curable coatings were prepared and coded as C20AA‐0, C20AA‐20, C20AA‐40, and C20AA‐60, respectively, which were further cured under UV irradiation. The effect of C20AA loadings on the UV‐curing efficiency and final polymer performance were investigated. Consequently, the tensile strength, Shore D hardness, pencil hardness, gel content, water resistance, and glass‐transition temperature of the UV‐cured coatings were greatly improved upon the addition of C20AA. Impressively, with the incorporation of 40 wt% C20AA, the resultant UV‐cured coating exhibited highest double bond conversion, superior chemical resistance, and good flexibility. Additionally, all of the coatings showed outstanding transparency and good surface microstructures.