Relaxation Phenomena in Chitosan-Au Nanoparticle Thin Films

Polymers

Elodie Strupiechonski¹  Evgeny Prokhorov²  Yuriy Kovalenko²  Gabriel Luna-Barcenas²  Marisa Moreno-Ríos³  Erika O. Ávila-Dávila³  Diana G. Zárate-Triviño⁴  Dora I. Medina⁵  Ramón Román-Doval⁶ 

[1] CONACYT—Cinvestav Unidad Queretaro, Queretaro 76230, Mexico;Cinvestav Unidad Queretaro, Queretaro 76230, Mexico;Department of Mechanical Engineering, Tecnologico Nacional de Mexico, Instituto Tecnologico de Pachuca, Pachuca 42083, Mexico;Laboratorio de Inmunología y Virología, Universidad Autónoma de Nuevo León, Monterrey 64450, Mexico;Tecnologico de Monterrey, School of Engineering and Sciences, Atizapan de Zaragoza, Estado de Mexico 52926, Mexico;Tecnológico Nacional de México, Instituto Tecnológico del Valle de Etla, Abasolo S/N, Barrio del Agua Buena, Santiago Suchilquitongo, Oaxaca 68230, Mexico;

关键词: Au-Chitosan nanocomposite;    glass transition;    relaxation phenomena;    dielectric spectroscopy;    dynamic mechanical behavior;   

DOI  :  10.3390/polym13193214

来源: DOAJ

【 摘 要 】

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.

【 授权许可】

Unknown