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Article

Relaxation Phenomena in Chitosan-Au Nanoparticle Thin Films

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CONACYT—Cinvestav Unidad Queretaro, Queretaro 76230, Mexico
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Department of Mechanical Engineering, Tecnologico Nacional de Mexico, Instituto Tecnologico de Pachuca, Pachuca 42083, Mexico
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Tecnológico Nacional de México, Instituto Tecnológico del Valle de Etla, Abasolo S/N, Barrio del Agua Buena, Santiago Suchilquitongo, Oaxaca 68230, Mexico
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Cinvestav Unidad Queretaro, Queretaro 76230, Mexico
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Laboratorio de Inmunología y Virología, Universidad Autónoma de Nuevo León, Monterrey 64450, Mexico
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Tecnologico de Monterrey, School of Engineering and Sciences, Atizapan de Zaragoza, Estado de Mexico 52926, Mexico
*
Authors to whom correspondence should be addressed.
Academic Editor: Sofia Rangou
Polymers 2021, 13(19), 3214; https://doi.org/10.3390/polym13193214
Received: 1 July 2021 / Revised: 31 July 2021 / Accepted: 3 August 2021 / Published: 23 September 2021
(This article belongs to the Section Polymer Membranes and Films)
Chitosan–gold nanoparticle (CS/AuNP) thin films were synthesized through the chemical reduction of HAuCl4 in sodium citrate/chitosan solutions. The dielectric and dynamic mechanical behaviors of CS/AuNP films have been investigated as a function of moisture and HAuCl4 content. Two relaxation processes in the nanocomposites have been observed. The α-relaxation process is related to a glass transition in wet CS/AuNP films. However, in dry composites (with 0.2 wt% of moisture content), the glass transition vanished. A second relaxation process was observed from 70 °C to the onset of thermal degradation (160 °C) in wet films and from 33 °C to the onset of degradation in dry films. This relaxation is identified as the σ-relaxation and may be related to the local diffusion process of ions between high potential barriers in disordered systems. The α- and σ-relaxation processes are affected by the HAuCl4 content of the solutions from which films were obtained because of the interaction between CS, sodium succinate, and gold nanoparticles. With about 0.6 mM of HAuCl4, the conductivity of both wet and dry films sharply increased by six orders, corresponding to the percolation effect, which may be related to the appearance of a conductivity pathway between AuNPs, HAuCl4, and NaCl. View Full-Text
Keywords: Au-Chitosan nanocomposite; glass transition; relaxation phenomena; dielectric spectroscopy; dynamic mechanical behavior Au-Chitosan nanocomposite; glass transition; relaxation phenomena; dielectric spectroscopy; dynamic mechanical behavior
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MDPI and ACS Style

Strupiechonski, E.; Moreno-Ríos, M.; Ávila-Dávila, E.O.; Román-Doval, R.; Prokhorov, E.; Kovalenko, Y.; Zárate-Triviño, D.G.; Medina, D.I.; Luna-Barcenas, G. Relaxation Phenomena in Chitosan-Au Nanoparticle Thin Films. Polymers 2021, 13, 3214. https://doi.org/10.3390/polym13193214

AMA Style

Strupiechonski E, Moreno-Ríos M, Ávila-Dávila EO, Román-Doval R, Prokhorov E, Kovalenko Y, Zárate-Triviño DG, Medina DI, Luna-Barcenas G. Relaxation Phenomena in Chitosan-Au Nanoparticle Thin Films. Polymers. 2021; 13(19):3214. https://doi.org/10.3390/polym13193214

Chicago/Turabian Style

Strupiechonski, Elodie, Marisa Moreno-Ríos, Erika O. Ávila-Dávila, Ramón Román-Doval, Evgeny Prokhorov, Yuriy Kovalenko, Diana G. Zárate-Triviño, Dora I. Medina, and Gabriel Luna-Barcenas. 2021. "Relaxation Phenomena in Chitosan-Au Nanoparticle Thin Films" Polymers 13, no. 19: 3214. https://doi.org/10.3390/polym13193214

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