Realization of integrative hierarchy by in-situ solidification of ‘semi-cured’ microcilia array in candle flame for robust and flexible superhydrophobicity

Abstract

Flexible superhydrophobic surfaces have recently attracted extensive interest owing to the potential for diverse curvatures and emerging flexible electronics. However, the simultaneous realization of mechanical robustness, chemical resistance, and maintained superhydrophobicity during deformation is still challenging. Herein, we introduced an environmental-friendly method to produce the integrative multi-level structures by generating the micro-cilia array in a ‘template-free’ manner, followed with in-situ thermal curing in the candle flame before the complete solidification of the micro-structured surface. Instead of weak physical adhesion (van der Waals forces), the candle soot nanoparticles penetrated into the ‘semi-cured’ micro-cilia surface, along with the high temperature to rapidly cure and generate the PDMS-connected integrative architectures, which effectively avoid the interface between the micro/nano-scaled components to eliminate the mechanical fragility. Comparative investigations confirm that the elevated robustness is attributed by the synergistic effect from the ‘semi-cured’ surface and the formation mechanism of subsequent hierarchical structures. The flexible film thus exhibits significantly improved stability against mechanical damage (ultrasonic processing, adhesive pressing, and linear abrasion), chemical corrosion, and water-jet impalement (∼10.4 m s−1 at ∼ 0.17 MPa). With the realization of co-existent features and real-life applications, the green methodology should be promising to open up an avenue that moves superhydrophobicity further to our world.