Polydopamine-based synthesis of an In(OH)3–PDMS sponge for ammonia detection by switching surface wettability

An In(OH)3–PDMS sponge has been synthesized by covalent modification of PDA. The sponge can switch surface wettability reversibly between superhydrophobicity and superhydrophilicity when detecting ammonia. The water contact angle changes from 141.5° to 0° after storage in an ammonia atmosphere, which means an ammonia responsive surface wettability switch. The minimum NH3·H2O concentration that the In(OH)3–PDMS can detected is 5% in 2 h. This kind of quick and sensitive ammonia detector is promising simply by virtue of the surface wettability conversion.