Synthesis and reactivity of novel cinnamonitrile derivatives as reactive UV stabilizers for enhanced light protection and performance of coatings

Ultraviolet (UV) light is generally harmful to human health and organic compounds (for example, plastics) as it deteriorates the long-term stability via photodegradation. Thus, an efficient strategy for reducing light-induced damage is the key to maximizing the operation lifetime or durability of materials. The most common means of preventing UV light-induced damage is by adding compounds that possess excellent UV absorbing capability. In this study, novel cinnamonitrile derivatives were designed and synthesized for their application as UV absorbers in pressure-sensitive adhesives. Absorption wavelengths were finely tuned by simple structural modification, and better molar absorptivity was obtained. The hydroxyhexyl functional group affixed into the cinnamonitrile core granted superior solubility (>10 wt%) in common organic solvents and acrylic monomers/resins, instigating enhanced UV blocking and visible light transparency. Further, to enhance the solubility and long-term stability of UV absorbers within a network, hydroxyhexyl-functionalized cinnamonitrile UV absorber was incorporated into urethane-based crosslinkers. Covalently attached reactive UV absorbers improved the adhesion property even at a high loading of UV absorber and remarkable physical persistence within the network.