Solvent influence on crosslinking and surface characteristics of Urushi films

Precision synthesis of 3-substituted urushiol analogues and the realization of their urushiol-like performance

“…Before polymerization, UA3 exhibits the characteristic broad phenolic O–H at around 3250 cm −1 , Ar-H and alkenyl C–H at 3016 cm −1 , strong saturated C–H absorption at about 2800–2980 cm −1 , carbonyl at 1650 cm −1 , phenyl ring band at about 1445 cm −1 , and the phenylic O–H bending at ∼1280 cm −1 . 28 After polymerization, several variations in the spectrum are noticeable; for example, the significant decrease in C–H stretching at 3016 cm −1 , combined enhancement of the phenyl ring band at about 1370–1520 cm −1 , and the newly appeared strong bands at about 1236 and 976 cm −1 . The decrease in the C–H stretching absorption can be attributed to the participation of C C bonds in the polymerization; the enhancement of the phenyl ring band may result from the coupling of phenyl rings, and the appearance of adsorptions at about 1236 and 976 cm −1 can be ascribed to the formation of aromatic ether bonds and trans C C bonds, respectively, in the polymerization.…”

Curing of Air-Drying Paints: A Critical Review

“…Curing of the oriental lacquers is a very slow process, and the final films are tough, brilliant, and resistant to water, alcohol, and oils but sensitive to UV radiation. 90 The most highly appreciated lacquer, known as "urushi", originates from Toxicodendron vernicifluum, grown in Japan, China, and Korea. 6,93 Its chief component, responsible for cross-linking, is a phenolic lipid called urushiol.…”

“…Alternative curing procedures involve thermal treatment enforced by iron(II) acetate 245 and UV curing of the lacquer solution in a reactive solvent. 90 In the first step of the polymerization, the catechol moieties of urushiol, laccol, and thitsiol are oxidized to semiquinone radicals. Such radical species are stabilized by resonance but readily attack other catechol moieties to give a mixture of biphenyls undergoing subsequent oxidation to dibenzofuran derivatives (Scheme 28).…”

“…succedaneum, and Gluta usitata. , The tree sap, harvested by tapping, is a latex material given after processing a self-cross-linking resin. Curing of the oriental lacquers is a very slow process, and the final films are tough, brilliant, and resistant to water, alcohol, and oils but sensitive to UV radiation …”

“…It is due to the antioxidant behavior of the phenolic compounds inhibiting the autoxidation process on lipid tails. , The oriental lacquers undergo the enzymatically catalyzed oxidative polymerization. Alternative curing procedures involve thermal treatment enforced by iron­(II) acetate and UV curing of the lacquer solution in a reactive solvent . In the first step of the polymerization, the catechol moieties of urushiol, laccol, and thitsiol are oxidized to semiquinone radicals.…”