Electrodewetting of Surfactant-Laden Drops on Silicon Oxide: Molecular Insights from Sum-Frequency Generation Spectroscopy

O molecules, along with silanol groups. Upon EDeW, no significant changes in SFG spectra were observed far from the contact line, but locally, the exposed surface exhibits a thicker and more disordered DTAB-rich layer, consistent with a hemimicellar structure. Our data suggest that EDeW involves electrophoretic transport of DTAB along the liquid-vapor interface toward the contact line, where surfactant deposition modifies the solid-vapor interface to become more hydrophobic. This mechanism explains the observed contact angle increase and highlights the critical role of interfacial surfactant organization in the EDeW.