Nylon, the basic element of transparent electronic devices?

Scientists at the Max Planck Institute for Polymer Research (MPI-P), led by Dr. Kamal Asadi, have solved the problem of producing very thin nylon films that can be used in electronic memory components , for example. Thin nylon films are several hundred times thinner than a human hair and could therefore be attractive for applications in curvable electronic devices or for electronics in clothing.

As the microelectronics industry evolves into electronic clothing and electronic textiles, researchers are incorporating electronic materials such as ferroelectrics to textiles. Nylons, a family of synthetic polymers, were introduced for the first time in the 1920s for women's stockings and are now one of the most widely used synthetic fibers in textiles. They consist of a long chain of repeating molecular units, i.e. polymers, in which each repeating unit contains a specific arrangement of hydrogen, oxygen and nitrogen with carbon atoms.

Nylons also have so-called "ferroelectric" properties. This means that the positive and negative electrical charges can be separated and this state can be maintained. Ferroelectric materials are used in sensors, actuators, memory devices and energy recovery. The advantage of using polymers is that they can be liquefied with appropriate solvents and thus converted into a low cost solution to form flexible thin films suitable for electronic devices such as capacitors, transistors and diodes. This makes ferroelectric polymers a viable choice for integration with electronic textiles. Although nylon polymers have important commercial applications in fabrics and fibers, their application in electronic devices has been hampered by the fact that it was impossible to create high quality thin films of nylons ferroelectrics by solution treatment.

The scientists of MPI-P, together with researchers from the Johannes Gutenberg University of Mainz and the Lodz University of Technology, have solved this 40-year-old problem and developed a method of manufacturing ferroelectric nylon thin film capacitors by dissolving the nylon in a mixture of trifluoroacetic acid and acetone and again solidifying it under vacuum. They were able to make thin nylon films with a thickness of typically 100 nanometers, which is several times thinner than hair. "By using this method, we have produced extremely smooth thin films, which is very important, because it avoids electrical failures, for example, of capacitors, and consequently the destruction of electronic circuits. thin transparent films, and finally, transparent electronic devices, "says Dr Kamal Asadi, group leader at MPI-P.

Using their newly developed method, the group around Kamal Asadi has been able to produce high performance nylon capacitors. Scientists have subjected prototypes of capacitors to prolonged stress cycles and have demonstrated the robustness of ferroelectric nylons in millions of operating cycles. Thin nylon films could become an important component for use in flexible electronics in the future and find applications in electronic devices that can be bent or for electronics in clothing. These new discoveries pave the way for multifunctional fabrics that serve as a fabric to cover our body and can at the same time generate electricity from the movements of our body.

Their results have now been published in the journal Progress of science.