title: Synthesis of triplet-triplet annihilation upconversion nanocapsules under protective conditions.
abstract: Triplet-triplet annihilation upconversion (TTA-UC) nanocapsules are synthesized under oxygen-protective conditions (i.e., complete darkness and argon atmosphere) by free-radical miniemulsion polymerization. These conditions help to exclude the oxidation of the emitter molecules caused by singlet oxygen, generated during the synthesis at daylight conditions and oxygen-rich environment. Subsequently, keeping all the other experimental conditions the same, samples synthesized at protective conditions demonstrate substantially increased UC efficiency. These experimental facts strongly support the hypothesis that posterior removing of oxygen from TTA-UC nanocapsules is not sufficient to obtain reproducible and sustainable UC results. The schematic representation shows the influence of sunlight on the formation of singlet oxygen and its effect on the triplet-triplet annihilation upconversion process.
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors: Kartheek
authors: K
authors: Katta
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors: Dmitry
authors: D
authors: Busko
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors: Yuri
authors: Y
authors: Avlasevich
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors: Rafael
authors: R
authors: Muñoz-Espí
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.|Optics and Spectroscopy Department, Faculty of Physics, Sofia University "St. Kliment Ochridski", 5 James Bourchier, 1164, Sofia, Bulgaria.
authors: Stanislav
authors: S
authors: Baluschev
authors: Max Planck Institute for Polymer Research, Ackermannweg 10, 55128, Mainz, Germany.
authors: Katharina
authors: K
authors: Landfester
mesh_terms: D056831:Coordination Complexes / Q000737:chemistry; D053769:Nanocapsules / Q000737:chemistry* / Q000648:ultrastructure; D010165:Palladium / Q000737:chemistry; D011789:Quantum Theory; D026082:Singlet Oxygen / Q000737:chemistry; D013050:Spectrometry, Fluorescence
chemical_list: D056831:Coordination Complexes; D053769:Nanocapsules; D026082:Singlet Oxygen; D010165:Palladium
keywords: free-radical polymerization; nanocapsules; photochemistry; polystyrene; triplet-triplet annihilation upconversion