High conductive Ag nanowire–polyimide composites: Charge transport mechanism in thermoplastic thermostable materials

Abstract

High conductive composites were elaborated by incorporating high aspect ratio (250) silver nanowires in polyimide matrix via solvent mixing way. Silver nanowires were synthesized in solution by polyol synthesis. The composite conductivity reaches the value of 102 S·m−1 above a very lowpercolation threshold (0.48 vol.% of silver nanowires). SEM-FEG images showed that metallic nanowires are well dispersed in PI matrix. They do not influence the physical structure of the polymer. Below the percolation threshold, γ, β and α relaxation modes were detected. γ relaxation mode was fitted to determinate the activation energy value (32.7 kJ·mol−1) and the relaxation time (1.5 × 10−16 s). The mobility associated with the γ relaxation is considered to be localized and non-cooperative. According to the Mott theory, studies on composites below the percolation threshold showed that the conduction mechanism is ruled by tunneling at low temperatures. The transport mechanism led by hopping is activated at −50 °C.