A low-cost filler-dissolved process for fabricating super-hydrophobic poly(dimethylsiloxane) surfaces with either lotus or petal effect

A low-cost filler (salt) water-dissolved method is developed to produce large-area and flexible super-hydrophobic surfaces by using poly(dimethylsiloxane) (PDMS) material. Five levels of salt grain sizes are used to examine the filler size effect on fabricating the super-hydrophobic surfaces and on the hydrophobic mechanism involved. The results show that the surfaces fabricated using grain sizes of 53-74 and 74-104μm exhibit the lotus effect (cell adhesion (CA) > 150° and self-adhesion (SA) < 10°); whereas those using grain sizes of 0-25μm and above 104μm reveal the petal effect (CA > 150° and high adhesion even upside-down). The super-hydrophobic characteristic is achieved mainly by the large micro rib-like structures, small micro rock-like bumps, and textures on the bump due to the fillers.