Hard transparent nanogradient coating for ultradurable omniphobic liquid-like surface

Abstract

Omniphobic liquid-like surface (LLS) offers excellent dynamic liquid repellency owing to the highly mobile polymer chains mediating at the solid–liquid interface. These polymer chains, often achieved by surface grafting, are not durable against abrasion or oxidation, which seriously hinders their practical application. Here we report a new vapor-based approach to create transparent nanogradient coating for LLSs with unprecedented mechanical strength and durability. The nanogradient coating is composed of a sandwich structure with an ultrathin primer, a rigid bulk, and a nanocomposite surface with abundant polydimethylsiloxane-like chains, all of which achieved via sequential plasma polymerization of a linear and a cyclic siloxane. The plasma-polymerized cyclic siloxane enables coating good mechanical strength while the plasma-polymerized linear siloxane confers coating sub-nanometer roughness and excellent dynamic liquid repellency. The resultant coating exhibits contact angle hysteresis < 5° towards many low-surface-energy liquids, as well as good mechanical strength with the hardness exceeding 1 GPa and superior durability enduring 100,000 cycles of abrasion. The coating also survived industrial standard thermal and accelerated UV-aging tests without losing its liquid repellency and transparency. The reported method is facile, scalable, and substrate-independent, offering exciting new opportunities towards industrial fabrication and real-world application of LLS.