Spectroscopic properties as a function of fluorine content in Eu3+:PMMA

In this work europium was used as a spectroscopic probe of the local environment about a lanthanide dopant in a fluorinated copolymer of poly(methyl methacrylate) (PMMA). Fluorination of PMMA was achieved through copolymerization with heptafluorobutyl methacrylate (HFBMA). Samples were characterized for their refractive index, glass transition temperature (T_g), and optical emissions via prism coupling, differential scanning calorimetry, and fluorescence spectroscopy respectively. The refractive index and T_gs were found to decrease linearly with fluorine content. The hypersensitivity ratio, which is defined as the ratio of integrated emission intensity between the ⁵D₀ → ⁷F₂ hypersensitive transition and ⁵D₀ → ⁷F₁ magnetic dipole transition in Eu³⁺, was found to decrease by ～60% when the HFBMA copolymer content exceeded about 75% by weight. This implies a change in the local environment about the rare earth dopant that is dependent on the copolymer concentration and is likely due to changes in solubility between the ligand and host environment. The results show that fluorination of PMMA can be useful to tailor refractive index, glass transition, and the spectroscopic properties of active dopants. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1592–1596, 2006