Synthesis and Characterization of a Perovskite Nanocomposite of CdTiO3@S with Orthorhombic Structure: Investigation of Photoluminescence Properties and Its Photocatalytic Performance for the Degradation of Congo Red and Crystal Violet Under Sunlight

Fukina

et al. 2023

Life

Graft copolymerization of methyl methacrylate onto cod collagen was carried out under visible light irradiation (λ = 400–700 nm) at 20–25 °C using the RbTe1.5W0.5O6, CsTeMoO6, and RbNbTeO6 complex oxides with β-pyrochlore structure as photocatalysts. The as-prepared materials were characterized by X-ray diffraction, scanning electron microscopy, and UV-Vis diffuse reflectance spectroscopy. It was also found that RbNbTeO6 with β-pyrochlore structure was not able to photocatalyze the reaction. Enzymatic hydrolysis of the obtained graft copolymers proceeds with the formation of peptides with a molecular weight (MW) of about 20 and 10 kDa. In contrast to collagen, which decomposes predominantly to peptides with MW of about 10 kDa, the ratio of fractions with MW of about 10 kDa and 20 kDa differs much less, their changes are symbatic, and the content of polymers with MW of more than 20 kDa is about 70% after 1 h in the case of graft copolymers. The data obtained indicate that synthetic fragments grafted to the collagen macromolecule do not prevent the hydrolysis of the peptide bonds but change the rate of polymer degradation. This is important for creating network matrix scaffolds based on graft copolymers by cross-linking peptides, which are products of enzymatic hydrolysis.

Section: Introductionmentioning

confidence: 99%

Photocatalytic Synthesis of Materials for Regenerative Medicine Using Complex Oxides with β-pyrochlore Structure

Семенычева

Fukina

et al. 2023

Life

“…Photocatalytic reactions under the influence of visible light attract attention due to compliance with the principles of green chemistry and the wide range of possibilities with their use. Different metal oxides, which are capable of catalyzing reactions under visible light irradiation rather than ultraviolet, have recently become the most widespread [1][2][3][4][5].…”

Section: Introductionmentioning

confidence: 99%

“…It is due to the presence of variety active particles in the reaction volume: charged particles, radicals, singlet oxygen, hydrogen peroxide, capable of destroying organic compounds. Significant progress has been recently reached in this direction [1,[6][7][8][9][10][11][12][13][14][15][16][17].…”

Section: Introductionmentioning

confidence: 99%

The effect of methyl methacrylate transformations during photocatalysis in the presence of RbTe1.5W0.5O6 on the change of the complex oxide surface

Izvestiâ vuzov. Prikladnaâ himiâ i biotehnologiâ

Fukina

Boryakov

et al. 2022

The features of the surface changes of the RbTe1.5W0.5O6 photocatalyst during polymerization processes involving methyl methacrylate (MMA) under irradiation with visible light λ= 400–700 nm at a temperature of 20–25 °C, as well as regeneration conditions for its reuse, have been studied. The realization of a chemical reaction in a mixture of a photocatalyst and a monomer is determined by its kinetic parameters and the concentration of reacting particles. The formation of OH• radicals, which are active in radical polymerization, occurs in this case by both ways: interacting between water molecules adsorbed on the surface, as well as during the recovery of oxygen dissolved in water. Due to the high reactivity of the hydroxyl radical, an active process of radical polymerization of MMA could be expected. However, the formation of polymethyl methacrylate (PMMA) in the reaction takes place with a low conversion – the formation of 5–10% polymer, which is related to changes on the surface of the complex oxide RbTe1.5W0.5O6 during the reaction. Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) methods have been used to investigate the catalyst surface. The presence of organic and polymer substrates was revealed on the catalyst surface after the reaction. As a result of the catalyst treatment by ultrasound in an aqueous emulsion, polymer macromolecules are not identified on the surface, but chemically adsorbed monomer and oligomers formed under the ultrasound destruction of the polymer are presented. Other methods of cleaning the catalyst surface by washing in different solutions as chloroform and tetrahydrofuran also are not effective and cause the adsorbates transformations on the surface. It leads to decreasing the RbTe1.5W0.5O6 catalyst's activity for repeated polymerization. Thus, to successful regeneration of the catalyst's powder not only ultrasound treatment is required, but also heating it at 300–400 °C to remove organic substrates.

“…The photocatalytic water splitting with the formation of hydrogen and organic compounds decomposition in aqueous solutions to carbon dioxide and water suggest either direct interaction with reactive hydroxyl radicals formed as a result of complex transformations of electron-hole pairs, or with oxidizing centers on the photocatalyst surface [1][2][3][4][5][6][7][8][9][10]. The formation of an active hydroxyl radical in the reaction system is of interest for organic synthesis, primarily for the production of new polymer materials without material initiators fragments with organic nature [9,11]. The complex oxide RbTe1.5W0.5O6 with βpyrochlore structure has been synthesized recently.…”

Section: Introductionmentioning

confidence: 99%

Features of Polymerization of Methyl Methacrylate using a Photocatalyst—the Complex Oxide RbTe1.5W0.5O6

Семенычева

J Inorg Organomet Polym

Matkivskaya

et al. 2021

Radical polymerization of methylmethacrylate in an aqueous emulsion was carried out using the complex oxide RbTe1.5W0.5O6 as a photoinitiator under visible light irradiation with λ= 400-700 nm. Studies of the process and reaction products using modern methods of physical and chemical analysis (GPC, IR, NMR, etc.) have shown that several directions of monomer transformations occur simultaneously in the reaction mixture. Polymethylmethacrylate, produced in the organic phase and characterized by Mn ~ 140-145 kDa, is a result of polymerization initiation by a hydroxyl radical formed due to complex transformations of electron-hole pairs during irradiation of the photocatalyst. Moreover, the interaction of the hydroxyl radical with OH groups on the complex oxide RbTe1.5W0.5O6 surface and the subsequent formation of oxygen-centered radicals lead to grafting polymer macromolecules onto the photocatalyst surface. In addition, methylmethacrylate is able to oxidize to a cyclic dimer with terminal double bonds and then form a polymer with cyclic dimer links due to coordination by double bonds on the complex oxide RbTe1.5W0.5O6 surface. The high activity of the hydroxyl radical made it possible to obtain the graft copolymer PMMA-pectin by grafting the polymer product onto the surface of the natural polymer-pectin. Comparison of the sponge morphology of the graft copolymer PMMA-pectin and the initial pectin samples using the scanning electron microscopy method showed a noticeable difference in their structural and topological organization. This fact is especially interesting in terms of studying the properties of the graft copolymer as a material for the scaffolds.