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Photosensitized hybrid coatings based on polyurethane matrices and metal oxide nanoparticles with tailorable photocatalytic features
Project status: Ongoing
EN / RO
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EXECUTION STAGE 1/2022

 Development of metal oxide nanoparticles, fluorescent organic precursors and of the corresponding polyurethanes

 

The activities proposed for the first stage of the project were:

1.1. Synthesis and functionalization of metal oxide nanoparticles (TiO2, ZnO, MnO2) - Objective 1.1.

1.2. Preparation of fluorescent monomers (diols of coumarin, dansyl or pyrene) to be used in polyurethane synthesis - Objective 1.2.

1.3. Design and synthesis of new polyurethane elastomers bearing fluorescent sequences - Objective 2

 

All the proposed activities were addressed and completed, the main results being summarized as follows:

In accordance with the proposed objectives, the first approached activity consisted in the synthesis of metal oxide nanoparticles, the studies carried out at this stage aiming the design and preparation of new zinc oxide nanoparticles. Although ZnO nanoparticles have a wide band gap energy (Eg = 3.37 eV), their major advantage compared to other photocatalysts is that they absorb a larger fraction of the UV spectrum. However, the wide band gap of the ZnO semiconductor results in low photocatalytic efficiency in the UV region due to the rapid recombination of photogenerated electron-hole pairs, which is why preventing the recombination of electron-hole pairs by reducing the band gap of ZnO nanoparticles (ZnO NPs) improves the photocatalytic performance. Therefore, a series of zinc oxide nanoparticles was synthesized, using various preparative conditions, their characterization being carried out by specific methods (FTIR spectroscopy, X-ray diffraction, scanning electron microscopy, EDX spectroscopy). In addition, the estimation of the band gap energy values shows that these varied for the synthesized ZnO NPs between 3.14 and 3.21 eV, and after functionalization with a silane-type derivative, the Eg value decreases to 2.97 eV.

The organic functionalization of ZnO nanoparticles with silane-type units and iodide ions was proposed as a convenient method of linking the inorganic units to the polyurethane chain through quaternization reactions, aiming a better dispersion of the nanoparticles in the organic matrix and preventing their migration during the photocatalytic activity testing.

In order to introduce fluorescent sequences into the polyurethanes chains, the synthesis and characterization (1H NMR, 13C NMR, FTIR, UV-Vis and fluorescence spectroscopy) of two types of diols bearing fluorescent units derived from coumarin was carried out, and the monomer with the best optical characteristics has been used in various ratios in the preparation of fluorescent polyurethane elastomers. The synthesized polyurethanes were also spectrally characterized to confirm the structure and to evaluate the optic characteristics, subsequent studies being directed towards the preparation of fluorescent polyurethane/ZnO nanoparticle hybrid nanocomposites and the testing of their photocatalytic activity under visible light irradiation.

 

Dissemination:

1. M. Murariu, Fluorescent polymeric sensors for metal ions detection and enhancement of sensing characteristics by Au NPs, XXXVI National Chemistry Conference, 4-7 October 2022, Calimanesti-Caciulata, Romania - oral presentation

2. V. Melinte, A.L. Chibac-Scutaru, V.E. Podasca, Synthesis, characterization and fluorescent behaviour of new polyurethane elastomers, XXXVI National Chemistry Conference, 4-7 October 2022, Calimanesti-Caciulata, Romania - poster

3. V.E. Podasca, V. Melinte, A.L. Chibac-Scutaru, Synthesis and characterization of zinc oxide particles for photocatalytic applications, XXXVI National Chemistry Conference, 4-7 October 2022, Calimanesti-Caciulata, Romania - poster

4. L. Stroea, M. Murariu, V. Melinte, The effect of various pollutant ions on a new coumarin-based sensor fluorescence, International Chemical Engineering and Material Symposium, SICHEM 2022,  17-18 November 2022, Bucureşti, Romania - oral presentation
 

 

 

 

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