Depolymerizable Polyimines Triggered by Heat or Acid as Binders for Conductive Inks

The ability to print electronic devices on soft substrates has the potential to revolutionize the world of consumable electronics. Electronic inks are typically constituted of an active nanomaterial dispersed in a solvent and stabilized by a surfactant which is necessary to impart colloidal stability. However, once the ink is applied, the surfactant presence in the final product is detrimental to the device performance. Here, we report the preparation of polyimines that can depolymerize and evaporate in the presence of light and heat. These polyimines were used for the formulation of Ag nanoparticle inks as well as for the dispersion of multiwalled carbon nanotubes (MWCNTs). In both cases, stable dispersions were obtained and were applied on a variety of substrates, leading to low-conductivity inks. However, the depolymerization and evaporation of the polyimine surfactant could be triggered by light and heat, then leading to a high-conductivity ink. By use of a laser engraver equipped with a CO2 laser, it was possible to spatially control the depolymerization of the MWCNT ink applied on a poly(ethylene terephthalate) film, while the nonexposed MWCNT ink was removed by simple solvent washing. Via this technique, it was possible to direct-write MWCNTs on a flexible substrate, thus demonstrating the potential of polyimines for the fabrication of electronic inks.

Automated summary

The ability to print electronic devices on soft substrates has the potential to revolutionize the world of consumable electronics. Polyimines were used to prepare electronic inks that can undergo depolymerization and evaporation triggered by light and heat, resulting in high-conductivity inks. The use of a laser engraver enabled the direct writing of multiwalled carbon nanotubes on a flexible substrate, demonstrating the potential of polyimines for electronic ink fabrication.