Fabrication of superhydrophobic insulation surfaces on PMMA by nanosecond-pulsed DBD in filamentary-homogeneous mixed mode

Superhydrophobic surfaces are in high demand for insulating materials because of their excellent self-cleaning property, which is advantageous to enhance their anti- wet and pollution flashover capability. Herein, we report on a one-step, energy-efficient and environment-benign process for fabricating superhydrophobic insulation surfaces on polymethylmethacrylate (PMMA) in an Ar/hexamethyldisiloxane(HMDSO) gas using nanosecond-pulsed DBD in homogeneous-filamentary mixed mode. The discharge mode judged by dynamic imaging with ICCD is maintained by controlling the HMDSO content and extending the discharge gap. It is found that the mixed discharge with filaments in the homogeneous plasma contributes to the fabrication of rough superhydrophobic film with robust mechanical stability, as further evidenced by SEM, AFM, FTIR, and XPS analysis. The film not only introduce shallow traps to accelerate potential decay and increase the dry flashover voltage, but also shrinks the wetting area to increase the wet flashover voltage 2.6 times that of the unprocessed PMMA. Moreover, results indicate that transformation from superhydrophilic to superhydrophobic surfaces can be fine-tuned by regulating the precursor content. The proposed strategy on the nanosecond pulse-driven discharge in mixed mode enables the effective fabrication of superhydrophilic and superhydrophobic surfaces and may provide practical guidelines for advanced surface engineering.