Janus nanosheets by emulsion interfacial crosslinking of reactive surfactants

Polymeric Janus nanosheets are synthesized by crosslinking the self-assembled monolayer formed by a reactive polymer surfactant at an oil/water interface. At low temperature, while the hydrophobic segments are frozen by the internal phase of solid paraffin, the reactive hydrophilic carboxylic acid groups exposed to the external aqueous phase can be selectively crosslinked to form an intact nanomembrane. The Janus nanosheets can be created after breaking the nanomembrane into pieces under ultrasonication during dissolution of the paraffin phase. Many approaches can be used to crosslink the nanomembrane at the interface, for example multiple amines and multivalent cationic ions. The polymeric Janus nanosheets can be easily functionalized to derive a series of composite nanosheets. The composite Janus nanosheets can serve as new solid surfactants which are responsive to pH or magnetic field.