Preparation and characterization of chalcone functional urethane acrylates for coating applications

New chalcone modified urethane acrylates (CMUA) were synthesized by the reaction of photoactive 4,4′dihydroxychalcone and polyethylene glycol 1000 (PEG-1000) with isophorone diisocyanate (IPDI) and followed by end-capping with 2-hydroxyethyl methacrylate (HEMA). The structure of CMUA oligomers was characterized by FT-IR and 1H NMR spectroscopies. Photosensitivity of CMUA oligomers was confirmed by using UV-vis absorption spectroscopy. The UV-curable clear coatings were prepared by the incorporation of CMUA oligomers into formulations together with reactive diluents such as dipropylene glycol diacrylate (DPGDA), 1,6-hexanediol diacrylate (HDDA) and photoinitiator and applied on Plexiglas plates and Teflon moulds. The physicochemical, mechanical and thermal properties of UV-cured coatings such as gel content, gloss, chemical-solvent resistance, contact angle, gloss, pendulum hardness, pencil hardness, tensile properties and char yield were investigated. The effect of chalcone modification on UV-cured CMUA coatings was evaluated and determined as the improvement in the properties of UV-cured coatings mainly due to the photocrosslinking ability of 4,4′dihydroxychalcone.