Synthesis of carboxylated-silver nanowires: Electrical conductivity enhancement of isotropic conductive adhesives and long-term stability in a mixture of solvents

Abstract

Incorporation of silver nanowires in conductive adhesives leads to the reduction of resistivity due to the increased surface area and reduction of contact resistance. However, due to high surface energy, aggregation in the adhesive polymeric matrix leads to performance decline. In this research, in order to solve the aggregation issue and increase the contact surface area, silver nanowires functionalized with carboxylate groups and 21.6 μm and 130.5 nm lengths and diameters were synthesized via polyol technique with a −49.7 mV zeta potential at pH = 7 in aqueous media (energy barrier ≈ 20 KBT). Also, functionalized nanowire suspension was stored in a mixture of solvents containing isopropyl alcohol, 1, 4-dioxane, and dimethyl sulfoxide maintaining stability for more than one year at the room temperature. Due to the good dispersion of the as-prepared silver nanowires in epoxy resin, increased adhesion density, reduction of air entrapment in the adhesive matrix during the curing process, and reduced oxidation rate, the as-prepared conductive adhesive with 50 wt% silver and 5 wt% polyethylene glycol showed a resistivity of 1.895 × 10-7 Ω cm.