Facile method to convert petal effect surface to lotus effect surface for superhydrophobic polydimethylsiloxane

The present study uses a facile method to produce a superhydrophobic polydimethylsiloxane (PDMS) surface with sandpaper molding and convert it from petal effect surface to lotus effect surface. This process increases the water contact angle (WCA) from 116.4° to 150.3°. The sandpaper-molded PDMS exhibits high adhesion for water droplets, that is, it has a petal effect surface. With perfluorodecyltrichlorosilane (PFDTS) solution immersion treatment of the PDMS, the contact angle hysteresis (CAH) reduces from 20.3° to 8.2° as the sliding angle (SA) reduces to 4°, that is, it has a lotus effect surface. This study presents a facile method to convert a petal effect surface to a lotus effect one for a rough PDMS surface. The chemical stability of fluorocarbons was tested in a solvent bath with 10 min ultrasonication. The results show that PFDTS can be grafted on sandpaper-molded PDMS surfaces without plasma pretreatment.