Contact Angle Goniometry Analysis of Gold-Silver Nanoshell Ink

Abstract

Colloidal conductive inks are rapidly gaining interest in the printing of flexible electronics. Many inks have been tested in various printing styles, but they all have their downfalls, ranging from cost to conductivity. This research looks at gold-silver nanoshells (GS-NS) and their potential use as an optically and electrically active colloidal ink. GS-NS have the advantages of lower cost than gold nanoparticles, the biocidal properties of silver nanoparticles, and a tunable range of absorption wavelengths due to localized surface plasmon resonance (LSPR). With these advantages of GS-NS in mind, various ink formulations were developed in this study and the physical properties analyzed. The solvents studied were: water, ethanol, ethylene glycol, and glycerol. Among the five inks formulations studied, four included hydroxypropyl cellulose (HPC) functionalized GS-NS used for better stability in solvents. Pendant drop and contact angle of the inks were analyzed on three different substrates: photo paper, polyethylene terephthalate (PET), and Teflon (PTFE). Each substrate varied in polarity and porosity. Droplet radius, droplet height, and spreading were calculated, and trends were analyzed, while also adding discussions on the dried droplet statistics. Overall, our studies demonstrate a fine balance between effective wetting while limiting spreading, to generate the best adhesion and precision