Synthesis and Characterization of Silver Nanowire Suspensions for Printable Conductive Media

Abstract

The purposes of this work are scaled-up synthesis of silver nanowires (AgNWs), assessment of their growth mechanism and measurement of the rheological properties of nanowire suspensions suitable for screen printing conductive circuits. A polyol synthesis process was used. The morphology and microstructure at various stages of the process were characterized by scanning electron microscopy (SEM). Aqueous silver nanowire inks with dispersant and binder were formulated. The rheological behavior of the inks was characterized by Stress Sweep Step (SSS), Steady State Flow Step (SSFS), Frequency Sweep Step (FSS) and Peak Hold Step (PHS) with a parallel plate rheometer. Rheological measurements under conditions that mimic the screen printing process have been done on the conductive inks through the PHS test to assess viscoelastic properties induced by flow alignment of the wires. Finally, the effect of silver nanowires on the rheological behavior of the ink has been compared with the effect of silver three-dimensional (3D) nanoparticles (AgNPs). Since most of the available commercial silver inks suitable for screen printing process are non-aqueous solvent based, a contribution of this study is formulation of an environmentally benign water based nanowire ink.