Photoreversible crosslinking of poly-(ethylene-butyl-acrylate) copolymers functionalized with coumarin chromophores using microwave methodology

Coumarin chromophores were successfully bonded onto ethylene-co-butyl acrylate (EBA) with a butyl ester content of 17% under mild conditions in solution via microwave irradiation. The synthesis consisted of three steps: partial conversion of butyl esters into carboxylic acid groups, conversion of carboxylic acid functionalities into acid chloride groups and esterification using 7-(3-hydroxy-propoxy) coumarin. The EBA modified with coumarin groups was characterized using FTIR, NMR, UV spectroscopy and thermal methods. The EBA modified with coumarin moieties (EBA-g-coum) was crosslinked by irradiating at 365 nm, and the coumarin photodimers were cleaved by irradiating at 280 nm. The reversibility of the photoreactions in the solid state was monitored using UV spectroscopy. Additionally, the mechanical properties of the materials were determined.