Polymers have gained importance in applications such as portable electronics due to their flexibility and light weight, but their low electrical conductivity is a major drawback. Although many research efforts have been made to improve conductivity, there are still technical limitations, such as the need to use harmful solvents and performance degradation in extreme environments.
The Korea Institute of Science and Technology (KIST) announced that it has developed a method for synthesizing polymers based on mixed ion-electron conductors through collaborative research with the Center’s Dr. Jang Ji-soo of Electronic Materials Research from KIST and Professor Mingjiang Zhong from Yale University, USA. This research overcomes the limitations of existing polymer conductors and is attracting attention as an innovative technology that can contribute to the development of the next generation of high-performance chemical sensors.
To solve this problem, researchers introduced ionic pendant groups into the polymer structure to synthesize conjugated polymers that can easily dissolve in environmentally friendly solvents rather than toxic solvents. In particular, polymers exhibit high performance in gas sensing in environmentally friendly processes and can maintain stable performance at high temperatures and humid environments. This technological advancement paves the way for applications in wearable devices, handheld electronics, and other electronic devices that can operate reliably in extreme environments.
Central to this research is the development of an ionization-based conjugated polymer soluble in an environmentally friendly solvent (2-methylanisole). While conventional conductive polymers typically require toxic solvents to dissolve, the new polymer significantly improves electrical conductivity by binding ionic species and electronic charge carriers. By introducing anions (TFSI-) and cations (IM+) into the polymer to increase the density and mobility of charge carriers, the team maximized conductivity and stability.
The n-type conductive polymer developed by the researchers, N-PBTBDTT, showed very high sensitivity in detecting harmful gases such as nitrogen dioxide (NO2). The sensitivity for NO2 detection reached 189% and the detection capacity was high even at a very low concentration of 2 ppb. This performance exceeds that of conventional sensing technologies, and the polymer has also proven to be highly resilient in environments with high humidity (80%) and high temperatures (up to 200°C). This enables stable gas detection in a variety of extreme environments, and is expected to be widely applied to wearable devices and industrial sensors.
« The sensors developed in this research go beyond simple chemical sensors and can bring revolutionary changes in various applications said Dr. Jang Ji-soo of KIST.
« IIt can especially serve as a life-saving material for people who work in extreme environments, such as firefighters who must detect harmful gases at fire scenes and soldiers who are exposed to chemical weapons in war. » concluded Junwoo Lee and Dr Juncheol Shin, first authors of the study.
Illustration caption: Ji-Soo Jang, Mingjiang Zhong and co-workers present polymeric mixed ionic-electronic conductors, consisting of charged monomers with ionic liquid-like pendant groups, that not only exhibit solubility in environmentally friendly solvents, but also long-term stability against humidity, high temperatures and mechanical deformation. Immobilized ionic species promote highly selective interactions of these polymers with nitrogen dioxide, paving the way for the development of stretchable sensing devices capable of operating at exceptionally high temperatures. Excerpt from the cover Advanced Functional Materials – Credit: Korea Institute of Science and Technology
Article : « Covalently Merging Ionic Liquids and Conjugated Polymers: A Molecular Design Strategy for Green Solvent-Processable Mixed Ion–Electron Conductors Toward High-Performing Chemical Sensors » – DOI: 10.1002/adfm.202408146
Source: KIST – Enerzine.com Translation
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