Highly dispersed polypyrrole nanotubes for improving the conductivity of electrically conductive adhesives

It is imperative to fabricate electrically conductive adhesives (ECAs) with excellent electrical performance and mechanical properties. In this article, a kind of polypyrrole nanotubes (PPy nanotubes) having a high aspect ratio and excellent dispersibility in various kinds of organic solvents were prepared and added to conventional Ag-containing adhesives. Stable suspension characteristics of PPy nanotubes in common solvents provided homogeneous dispersion of the PPy nanotubes in the composites. A small amount of PPy nanotubes can remarkably change the structures of the conductive networks of conventional ECAs and significantly improve the ECAs’ conductivity. By only adding 3 wt% PPy nanotubes, the resistivity (5.8 × 10⁻⁵ Ω ‧ cm) of the ECAs containing 55 wt% silver decreased to 1/1000 of the comparative ECAs without PPy nanotubes. This resistivity is almost five to one-tenth of the ECAs materials reported by now. Furthermore, the resulted ECAs showed excellent mechanical properties. The electrical resistivity of the new PPy nanotube-containing ECAs remained stable after they were rolled at a 6 mm bending radius for over 5000 cycles or pressed under 1200 kPa. An elastic printed circuit was fabricated using the above-described ECA-containing PPy nanotube, which demonstrates its potential application in the field of flexible electronics.