Tuning HAuCl 4 /Sodium Citrate Stoichiometry to Fabricate Chitosan-Au Nanocomposites

• Published in: Polymers Vol. 14; no. 4
• Main Authors: Torres-Ferrer, Luis R, López-Romero, José M, Mendez-Nonell, Juan, Rivas-Arreola, Maria J, Moreno-Ríos, Marisa, Ávila-Dávila, Erika O, Prokhorov, Evgeny, Kovalenko, Yuriy, Zárate-Triviño, Diana G, Revilla-Vazquez, Javier R, Meraz-Rios, Marco A, Luna-Barcenas, Gabriel
• Format: Journal Article
• Language: English
• Published: Switzerland 17.02.2022
• Subjects: chitosan-gold nanocomposites; HAuCl4/sodium citrate relationship; α-relaxation; σ-relaxation
• ISSN: 2073-4360

Nanocomposite engineering of biosensors, biomaterials, and flexible electronics demand a highly tunable synthesis of precursor materials to achieve enhanced or desired properties. However, this process remains limited due to the need for proper synthesis-property strategies. Herein, we report on the ability to synthesize chitosan-gold nanocomposite thin films (CS/AuNP) with tunable properties by chemically reducing HAuCl in chitosan solutions and different HAuCl /sodium citrate molar relationships. The structure, electrical, and relaxation properties of nanocomposites have been investigated as a function of HAuCl /sodium citrate molar relation. It was shown that gold particle size, conductivity, Vogel temperature (glass transition), and water content strongly depend upon HAuCl /sodium citrate relationships. Two relaxation processes have been observed in nanocomposites; the -relaxation process, related to a glass transition in wet CS/AuNP films, and the -relaxation related to the local diffusion process of ions in a disordered system. The ability to fine-tune both - and -relaxations may be exploited in the proper design of functional materials for biosensors, biomaterials, and flexible electronics applications.