Dynamic-Wetting Liquid Metal Thin Layer Induced via Surface Oxygen-Containing Functional Groups

Enhancing the wettability of liquid metals (LMs) to address their high surface tensions is crucial for practical applications. However, controlling LMs wetting on various substrates and understanding the underlying mechanisms are challenging. Here, we present a facile dynamic-wetting strategy to modulate eutectic gallium-indium (EGaIn) wettability via chemical surface modification, spontaneously forming a stable and thin (∼18 μm) EGaIn layer. Polymer substrates exhibiting varying EGaIn wetting behaviors can be categorized by their sliding angles and adhesion force. X-ray photoelectron spectroscopy results demonstrate that the dynamic-wetting process occurs only on surfaces with sufficient oxygen-containing functional groups (content ≥18%) and confirm coordination interactions between the EGaIn oxide layer and surface functional groups. Furthermore, in EGaIn thermal management systems, the heat transfer rate in the wetting group is increased by up to 20% compared to that of the nonwetting group. This work will hasten the application of LMs in flexible circuits and thermal management.