Egain

The EGaIn-SEBS composite film was prepared using the following procedure. First, 180 mg of SEBS (Tuftec™ H1062, Asahi Kasei Co., Chiyoda, Tokyo, Japan) was dissolved in 2 mL of toluene (Sigma-Aldrich, St. Louis, MO, USA) by stirring for 6 h at 200 rpm. Subsequently, 700 mg of EGaIn (12478, Alfa Aesar, Haverhill, MA, USA) was added to 2 mL of SEBS solution in a conical tube (Dongnam Chemical, Seoul, Republic of Korea). To homogenize the particles, the composite solution was subjected to tip sonication using a VCX–750 (Sonics & Materials Inc., Newtown, CT, USA) operating at a power of 300 W power for 10 min. The resulting EGaIn-SEBS solution was then drop-cast onto 3 cm × 3 cm octadecyl trichlorosilane (OTS)-treated glass substrates and left to evaporate at room temperature for 6 h. Finally, the composite was peeled off from the glass surface to complete the fabrication process. The LM particles in the drop-cast composite solution sank to the bottom during the evaporation process, thereby making the under and upper sides of the composite conductive and insulating parts, respectively.

To fabricate the EGaIn-SEBS composite, firstly, 180 mg of SEBS (Tuftec™ H1062, Asahi Kasei Co., Ltd., Tokyo, Japan) was dissolved in 1.5 mL of toluene (Sigma-Aldrich, Burlington, MA, USA). Subsequently, 400 mg, 700 mg, and 1 g of EGaIn (12478, Alfa Aesar, Ward Hill, MA, USA) were added to the solution, and tip sonication (VCX-750, Sonics & Materials Inc., Newtown, Connecticut, USA) was performed for 10 min at 300-W power. The EGaIn-SEBS solution was drop-casted in 2 cm × 2 cm glasses and evaporated at room temperature for 6 h to complete a homogeneous composite. Ag flakes (AgFs, DSF-500MWZ-S, Daejoo Electronic Materials Co., Ltd., Gyeonggi-do, South Korea) were used as solid-state fillers for comparison with EGaIn, which is a liquid-state filler. A total of 700 mg of AgFs was added to the toluene in which SEBS was dissolved, and the AgF-SEBS solution was dispersed well using a vortex mixer (MaXshake™ VM30, Daihan Scientific Co., Ltd., Gangwon-do, South Korea). Thereafter, the AgF-SEBS composite was fabricated in the same way as the aforementioned process. Finally, the microscopic structure and EDS (Energy Dispersive X-Ray Spectrometer) mapping of the composites were analyzed using FE-SEM (JSM-IT800, JEOL Co., Ltd., Tokyo, Japan).