A facile, fast, and low-cost method for fabrication of micro/nano-textured superhydrophobic surfaces

Hypothesis: Alkyl ketene dimer (AKD) is frequently used in paper industry as an inexpensive sizing agent. The formation of a porous structure after curing the solidified AKD for an extra-long time (4-6 days) results in superhydrophobicity. In this study, a facile and low-cost method was utilized to turn the surface of AKD superhydrophobic in a very short period of time. Experiments: We fabricated superhydrophobic coatings by dipping glass and paper substrates in molten AKD and then treating them with ethanol after solidification. The samples were characterized by X-ray diffraction, Scanning electron microscopy, Fourier transform-infrared spectroscopy, X-ray photoelectron spectroscopy, Confocal laser scanning microscopy, and dynamic contact angle goniometry. Findings: The results show that briefly treating the coatings, obtained from isothermally heated AKD melt at 40 degrees C for 3 min, with ethanol leads to superhydrophobicity with advancing and receding contact angles of 158.7 +/- 1.4 degrees and 156.8 +/- 0.9 degrees, respectively. By increasing the melt temperature to 70 degrees C and its heating time to 6 h followed by ethanol treatment, the advancing and receding contact angles increased to 163. 7 +/- 1.3 degrees and 162.6 +/- 1.2 degrees, respectively. This enhancement in superhydrophobicity is due to the formation of porous, entangled irregular micro/nano textures that create air cushions on the surface resulting in droplet state transition from Wenzel to Cassie. (C) 2020 Elsevier Inc. All rights reserved.