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The counterions of polydiallyldimethylammonium (PDADMA) coatings were altered by incubation in aqueous solutions of different electrolytes. Oil de‐wetting on the resulting polycationic surfaces upon water action exhibited a straightforward connection with the Jones–Dole viscosity B‐coefficient (Bη) sign of surface counteranions. Upon water action, surface counteranions with negative Bη render PDADMA coatings oil‐adhering, but those with positive Bη furnish PDADMA coatings with excellent self‐cleaning. The oil‐adhering PDADMA surfaces can become self‐cleaning upon water action in response to the Bη of surface counteranions sign‐switching with increasing water temperature. Courtesy of surface counter‐anions with Bη>0, self‐cleaning PDADMA coatings enable not only conversion of conventional meshes into self‐cleaning membranes for oil/water separation, but also regioselective maneuver of oil flow on polycationic surfaces according to the Bη sign of surface counteranions patterned atop. [ABSTRACT FROM AUTHOR]

Monodisperse,quasi-spherical silver nanoparticles (Ag NPs) withcontrolled sizes have been produced directly in water via adding theaqueous solutions of the mixtures of AgNO3and sodium citrateto boiling aqueous solutions of ascorbic acid (AA). Different compounds,including NaCl, NaBr, KI, Na2SO4, Na2CO3, Na2S, and Na3PO4, are added to the AgNO3/citrate mixture solutions toform new silver compounds with fairly low solubility in water, whichare used as precursors instead of soluble Ag+ions to synthesizeAg NPs via AA/citrate reduction. This enables us not only to producemonodisperse, quasi-spherical Ag NPs but also to tune the sizes ofthe resulting NPs from 16 to 30 nm according to the potential of newsilver precursors as well as the concentrations of anions. [ABSTRACT FROM AUTHOR]