Encapsulated silver nanoparticles in water/oil emulsion for conductive inks

Abstract Silver nanoparticle (AgNP) inks are the most commonly used conductive ink for printed conductive tracks. However, the ink stability against aggregation and sedimentation is poor and results in short shelf life, severe nozzle clogging, and bad printing qualities. Herein, a new method is developed to improve the stability of AgNP inks. In this work, a water-in-oil type emulsion is used as a carrier for water-based silver nanoparticles. Different water/surfactant ratio are examined for the complete AgNP uptake in water nano droplets. The morphology of AgNP after emulsification is carefully examined with electro-microscopy to elucidate the particle engulfment in water. The encapsulated AgNP show a much lower sedimentation rate due to the greatly reduced overall density of encapsulated AgNPs/water droplets. Moreover, the water/oil interfaces around AgNPs prevent aggregations, and thus leads to better long-term ink stability. The physical properties of AgNP emulsion meet the requirement of the printer and stable inkjet droplet can be produced. Conductive tracks with electrical resistance 4.92 μΩ-cm and line width 170 µm can be printed on photo papers, which demonstrates the potential of the emulsion for inkjet printing application.