Highly-Conductive Stretchable Electrically Conductive Composites by Halogenation Treatment and Its Application in Stretchable Electronics

Flexible electrically conductive composites (FECCs) are a promising group of materials for flexible electrodes and interconnections in next-generation flexible electronics. Silicone/silver-based electrically conductive composites are gaining more popularity because of their very high strain at break (stretchability), low processing temperature, and chemical/thermal stability. However, the low bulk conductivity of silicone-based FECCs negatively affects their performance as electrodes or interconnections. Moreover, the majority of silicone-based FECCs rely on an addition reaction to cure the composite with a platinum catalyst, which is vulnerable to poisoning by various chemicals. In the present study, we developed an effective method to increase the electrical conductivity of silicone-FECCs without affecting the curing process. KI was added to replace the lubricant and silver oxide layer on silver flakes and to form photosensitive silver halide. After exposing to sunlight, silver halide could photo-decompose into silver nanoparticles that cover the surface of silver flakes. We optimized the several parameters of the treatment, including the KI concentration, sunlight exposure time and the curing temperature of siliconeFECCs. In the optimized condition, the silicone FECCs exhibits the lowest resistivity of 1.88×10-4 ?·cm at 75 wt% loading. Their application as electrodes for electrocardiogram (ECG) monitoring is also demonstrated in this study.