Freestanding Ultrathin Nanoparticle Membranes Assembled at Transient LiquidLiquid Interfaces

(please note that in this context, we defi ne as membrane any freestanding thin layer, regardless of selective mass-transport properties). These approaches rely on the possibility of NPs to adsorb and pack into a dense network at an interface. This can occur if the free energy of the nanoparticles bound at the interface is lower than that of the NPs in either of the two phases. [ 38–40 ] The surface of NPs should thus possess specifi c wetting properties to guarantee a stable adsorption at the interface. Such behavior can be obtained using nanoparticles with a Janus-type anisotropic surface functionalization [ 41 ] or having systems that will spontaneously break their symmetry in situ. [ 42 ]