Emerging waste-free non-destructive system based on molecular sensors originating from novel europium complexes for in-situ determination of polymer coating thickness

Abstract Herein, novel europium(III) complex derivatives dedicated to polymer chemistry applications as molecular sensors have been reported. The following are among them tris(4,4,4-trifluoro-1-phenylbutane-1,3-dione)europium(III) (BTA) and tris(4,4,4-trifluoro-1-(2-naphthyl)butane-1,3-dione)europium(III)] (NTA). To obtain the relevant europium complexes, they were coordinated with the corresponding ligands, e.g., 4-phenyl-2,6-bis(2-pyridyl)pyridine (PPP), 2,2′-bipyridine (Bpy), 2-(2-pyridyl)-1,3-benzothiazole (PBT) and 2-(2-pyridyl)imidazo[1,2-a]pyridine (PIP). The application of these compounds as luminescent sensors to monitor the kinetics of cationic photopolymerisation of monomers has been investigated along with the determination of optical properties. Ultimately, the possibility of employing europium(III) complexes as thickness sensors for polymer coatings resulting from the free radical photopolymerisation of trimethylolpropane triacrylate was measured using Fluorescence Probe Technology developing a zero-waste, non-destructive method for in-situ determination of polymer coating thickness.