Polydopamine deposition at fluid interfaces

When catecholamine solutions are put in the presence of an oxidant, a spontaneous oxidation process allows one to coat the surface of all known classes of materials with a brown-black insoluble material. This material is related to eumelanins from both compositional and structural points of view. Simultaneously with the film deposition at solid/liquid interfaces, an insoluble material is obtained in solution. Under particular experimental conditions, the chemistry of catecholamines, mostly dopamine, can be extended to the water/air interface to produce films which can be handled and transferred on solid substrates. The mechanical properties of these polydopamine' films can be improved in a way allowing for the realization of micrometre-thick free-standing Janus-like films. Polydopamine films at liquid/liquid interfaces have also been found to stabilize microemulsions. The aim of this mini-review is to summarize these recent advances of catecholamine chemistry to obtain functional coatings at fluid interfaces. (c) 2016 Society of Chemical Industry