Added Iodine Makes Conductive Paints Easier, Cheaper to Produce — and Inkjet-Printable, Too

A team of researchers from the University of Tsukuba and the High Energy Accelerator Research Organization (KEK) has published a paper which could make flexible and universal electronics more readily accessible — by making it easier to produce electrically-conductive paint and other polymer alloys.

"Polyaniline is an extremely versatile polymer in routine and advanced technologies, but restrictions on which solvents can be used for synthesis have long hindered this versatility," says senior author Hiromasa Goto, professor at the University of Tsukuba, of his team's work. "Our discovery of how to facilitate polymerization in diverse solvents will be useful in basic research and industrial applications."

Electrically conductive paint, which can be used as simply as applying to a surface with a brush or a pen to create a hand-drawn circuit, is useful stuff — but not necessarily the simplest thing to make. Polyaniline-based conductive paint is presently made using relatively expensive solvents, which can now be replaced with lower-cost solvents with lower boiling points and less complex manufacturing processes.

"A particularly exciting result is the ease of preparing industrially useful polymer alloys, such as blends with polystyrene or cellulose derivatives," explains Goto. "Electrically conductive paint, advanced rubber blends, and other materials are now straightforward to prepare, which we expect will facilitate product development in diverse fields."

The team's work centres around the production of polyaniline from aniline sulfate using added iodine in the reaction mixture, reducing the process to a single step while expanding the types of solvents which can be used. As well as reducing the complexity and cost, the researchers claim the new technique opens up polyaniline to new manufacturing processes — including being used with an inject printer in order to quickly and easily make printed circuit boards and flexible electronics.

The team's work has been published under closed-access terms in the journal Polymer-Plastics Technology and Materials.