Liquid-like Slippery Surfaces via Ultrasound Activation and Grafting of Polydimethylsiloxane

Slippery molecular coatings that dynamically repel polar and nonpolar liquids are in urgent need for a diverse range of applications. Nanoscopic films of grafted polydimethylsiloxane (PDMS) have particularly attracted significant attention for their liquid-like slipperiness, which arises from their flexible chains and low surface energy. Herein, we present ultrasound-assisted activation and grafting of methyl-terminated PDMS for generating fluorine-free omniphobic coatings on silicon oxide-terminated surfaces. Intense sound waves generated by an ultrasonic homogenizer induce the activation of unreactive and inert PDMS, allowing ambient grafting in less than an hour. The grafted PDMS films with a thickness of ∼4 nm exhibit sliding angles below 17° for liquids with surface tensions ranging from 20 to 73 mN/m. The sonochemical activation of PDMS under outdoor conditions and its subsequent deposition over square meters of surfaces demonstrate the practical potential of the proposed method. The ultrasound activation enables the versatile preparation of liquid-like slippery molecular coatings over large areas using inexpensive materials and ambient processes.