Biodegradable conductive nanocomposites composed of poly(ε-caprolactone) and silver nanowires for advanced applications

• Main Author: Markovic, Miljana
• Publication Date: 2021
• Format: Master thesis
• Language: eng
• Source: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Download full: http://hdl.handle.net/10773/32407
• topic: Poly(ɛ-caprolactone); Silver nanowires; Biodegradable films; Advanced applications; Conductive nanocomposites

Technological progress strongly relies on the development of high-performance materials. However, numerous environmental problems associated with the over-exploitation of fossil resources made the process of material design much more demanding and, in particular, sustainable. In this context, the idea behind the present dissertation is to create a biobased conductive nanocomposite material for potential applications in various advanced areas. Specifically, the nanocomposite consists of a poly(ε-caprolactone) (PCL) matrix functionalized with silver nanowires (AgNWs). The main asset of this material is its biobased nature, as well as its improved mechanical and electroconductive performance. Firstly, silver nanowires were synthesized via the polyol method, and characterized by ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). Secondly, the PCL-based nanocomposite films with different percentages of AgNWs, namely 1, 2, 3 and 7.5% (w/w), were fabricated via the simple and fast solvent casting film-processing methodology. The ensuing nanocomposite films were characterized by Fourier transform infrared-attenuated total reflection (FTIR-ATR) spectroscopy, XRD, SEM, SEM/EDS mapping, thermogravimetric analysis (TGA), tensile tests, dynamic mechanical analysis (DMA), and dielectric measurements. Overall, the synthetized AgNWs were highly crystalline and presented a needle-like morphology. The incorporation of these nanowires into the PCL matrix generated nanocomposite films with thermal stability up to almost 325°C and good mechanical performance with Young’s modulus values higher than 350 MPa. Moreover, the electrical conductivity (σAC) of the PCL-based films was evaluated by impedance spectroscopy and reached a maximum value of 5.7×10-6 S m–1 (at 235 K and 1.0×106 Hz) for the nanocomposite with the highest content of AgNWs (7.5%, PCL/AgNWs_7.5). All the obtained results revealed the potentiality of these thermoplastic nanocomposite films as biobased electroconductive materials for advanced applications.