Optical and structural characteristics of PMMA films doped with a new anisometric Eu^III complex

A new film material capable of transforming UV radiation into visible light was obtained from a highly anisometric Eu^III complex with organic ligands in a polymethyl­methacrylate (PMMA) matrix and then structurally characterized. An important advantage of the synthesized complex is its good solubility in organic solvents such as di­chloro­methane, chloro­form, THF, toluene, etc. The ligand environment (flexible alkyl and cyclo­hexyl substituents) of the Eu^III complex was selected to prevent crystallization, to inhibit the formation of defects in the structure of films and to provide its uniform distribution in the polymer during polymerization. As a result we obtain an Eu^III complex of the film with remarkable thermal behavior: the complex melts to isotropic liquid without decomposition, it supercools at ambient temperature and it forms a stable amorphous material at low (up to −30°C) temperatures. The films were prepared by two methods: bulk polymerization and spin coating. A comparison of the differences of luminescent and optical characteristics of micro- and nanosized PMMA films doped with the anisometric Eu^III complex is given. Based on X-ray powder diffraction and small-angle scattering data, it has been supposed that the association of Eu^III complex molecules occurs in the voids of the PMMA matrix and is accompanied by the formation of a nanocrystalline phase. For films obtained by spin coating, a deeper microphase separation is demonstrated than by bulk polymerization. The dimensional characteristics of the nano-associates were determined and a correlation between the method of preparation and the type of distribution of the Eu^III complex in the PMMA matrix is established.