The new organic composite material is stretchable in two dimensions. Photo: Thor Balkhed.
The new organic composite material is stretchable in two dimensions. Photo: Thor Balkhed.

Researchers at the Laboratory of Organic Electronics at Linköping University in Sweden have developed an organic composite material with unique abilities – not only is it soft and stretchable, but it also has a high electrical conductivity and good thermoelectric properties. This makes it ideal for many wearable applications. Together with colleagues from Belgium, New Zealand and California, the researchers report their work in a paper in Nature Communications.

To produce the organic composite material, Nara Kim, postdoc and principal research engineer in the Laboratory of Organic Electronics, combined three materials: the conducting polymer PEDOT:PSS; a water-soluble polyurethane rubber; and an ionic liquid. The PEDOT:PSS gives the composite material thermoelectric properties, the rubber provides elasticity and the ionic liquid ensures softness.

Kim carried out this work under the leadership of Xavier Crispin and Klas Tybrandt, both at the Laboratory of Organic Electronics. "Xavier Crispin is a pioneer in organic thermoelectric materials, Klas Tybrandt is an expert in soft electronic materials, and I contribute my knowledge of organic composites," Kim explains. "We came up with the idea for the new material together."

PEDOT:PSS is the most common conducting polymer and is used in many applications, not least due to its good thermoelectric properties. But thick polymer film is too hard and brittle to be successfully integrated into wearable electronics.

"Our material is 100 times softer and 100 times more stretchable than PEDOT:PSS", says Tybrandt, who leads the group of Soft Electronics at the Laboratory of Organic Electronics. "The ability to control the structure of the material both at the nanoscale and the microscale allows us to combine the excellent properties of the different materials in a composite."

The new composite is also printable. "The composite was formulated by water-based solution blending and it can be printed onto various surfaces. When the surface flexes or folds, the composite follows the motion. And the process to manufacture the composite is cheap and environmentally friendly," says Kim.

The researchers envisage a huge range of new possibilities for using this approach to create soft and elastic organic conducting materials. "There are many ionic liquids, conducting polymers and traditional elastomers that can be combined to give new nanocomposites for many applications, such as thermoelectric generators, supercapacitors, batteries, sensors, and in wearable and implantable applications that require thick, elastic and electrically conducting materials," says Crispin.

This story is adapted from material from Linköping University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.