Bell‐Shaped Superhydrophilic–Superhydrophobic–Superhydrophilic Double Transformation on a pH‐Responsive Smart Surface

Abstract
Superhydrophobic to neutral water droplets, superhydrophilic to acidic or basic. This double transition of surface wettability in response to a single stimulus – pH – is demonstrated for the first time. The smart surface is composed of a rough gold surface modified with a self‐assembled monolayer (SAM) containing three thiols, HS(CH2)11CH3, HS(CH2)10COOH, and HS(CH2)11NH2. A ternary diagram is generated that describes wettability as a function of the SAM composition and the pH of the surrounding solution.