Browsing by Author "Bonardd, S."

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    A facile approach for tuning optical and surface properties of novel biobased Alginate/POTE handleable films via solvent vapor exposure
    (ELSEVIER, 2021) Mendez Lopez, M.; Ramos Hernandez, A.; Moreno Serna, V.; Bonardd, S.; Ramirez, O.; Silva, Hernan; Inostroza Rivera, Ricardo; Diaz, D. Diaz; Leiva, A.; Saldias, C.
    Novel biobased films consisting of alginate blends with poly (octanoic acid 2-thiophen-3-yl-ethyl ester) (POTE), a conducting polymer, were prepared by solution casting, and their optical, morphological, thermal, and surface properties were studied. Using UV-visible spectroscopy, atomic force microscopy (AFM), and scanning electron microscopy (SEM), the effects of tetrahydrofuran solvent vapors on the optical properties and surface morphology of biobased films with different POTE contents were studied. Results indicate that morphological rearrangements of POTE take place during the process of solvent exposure. Specifically, the solvent vapor induced the formation of POTE small crystalline domains, which allows envisioning the potential of tuning UV-visible absorbance and wettability behavior of biobased films. Finally, theoretical electronic calculations (specifically frontier molecular orbitals analysis) provided consistent evidence on POTE's preferential orientation and selectivity toward the THF-vapor medium.
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    Ferrocene-modified dendrimers as support of copper nanoparticles: evaluation of the catalytic activity for the decomposition of ammonium perchlorate
    (2022) Rios, P. L.; Araya-Duran, I.; Bonardd, S.; Arroyo, J. L.; Povea, P.; Camarada, M. B.
    Ferrocene (Fc)-based systems are frequently used as burning rate catalysts in the decomposition of ammonium perchlorate (AP)-based propellants. However, small Fc derivatives migrate to the surface of the propellant resulting in undesirable changes in the designed burning parameters and unstable combustion. To retard the migration and to increase the combustion rate of AP, fourth-generation polyamidoamine (PAMAM) dendrimers modified with Fc (PAMAM generation 4 [G41-Fc) were synthetized and used as support for the obtention of copper nanoparticles (CuNPs). PAMAM G4 produced smaller nanoparticles (1-2 nm) with lower aggregation than PAMAM G4-Fc (12-14 nm). X-ray photoelectron spectroscopy (XPS) characterization confirmed the superior stabilizing and protecting effect against oxidation of CuNPs by PAMAM G4 in comparison to PAMAM G4-Fc, whereas molecular dynamics simulations have shown less flexibility and lower presence of stabilizing sites for nanoparticles in PAMAM G4-Fc. Antimigration tests confirmed the negligible migration of PAMAM G4-Fc compared with Fc, whereas PAMAM G4-Fc vertical bar CuNP affected the high-temperature decomposition of AP positively, decreasing the decomposition temperature in 87 degrees C owing to a synergistic effect between CuNPs and Fc. PAMAM G4-Fc can act both as an effective antimigration system of Fc and as a stabilizing framework of metal nanoparticles with application as catalysts of AP. (C) 2021 Elsevier Ltd. All rights reserved.
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    In situ synthesis and immobilization of CuO nanoparticles in alginate-poly (amido amine) nanogels for photocatalytic applications
    (2022) Cordoba, A.; Duran, B.; Bonardd, S.; Diaz Diaz, D.; Leiva, A.; Saldias, C.
    Herein, we report a feasible approach for preparation of crosslinked alginate (Alg) and poly(amido amine) (PAMAM) nanogels (Alg-PAMAM NGs), using a water-in-oil-in-water (w/o/w) double emulsion route, via strong electrostatic interactions between anionic groups coming from alginate and previously incorporated Cu2+ ions. CuO nanoparticles (NPs) with average diameter about 65 nm were in situ obtained into Alg/PAMAM nanogels by treatment of embedded Cu2+ ions in NGs with NaBH4 at 25 degrees C under air atmosphere. The prepared Alg-PAMAM and Alg-PAMAM-CuO NGs were characterized using FT-IR and UV-visible spectroscopy, as well as scanning transmission electron microscopy (STEM). The presence of PAMAM dendrimers helped both to obtain structurally compact nanogels and an adequate stabilization of CuO NPs. Finally, the photocatalytic performance of the Alg-PAMAM-CuO NGs was tested via the decomposition of methyl orange in aqueous solution, under visible light irradiation.