Straightforward Preparation of Supramolecular Janus Nanorods by Hydrogen Bonding of End-Functionalized Polymers

Janus cylinders are one-dimensional colloids that have two faces with different compositions and functionalities and are useful as building blocks for advanced functional materials. Such anisotropic objects are difficult to prepare with nanometric dimensions. Here we describe a robust and versatile strategy to form micrometer long Janus nanorods with diameters in the 10-nanometer range, by self-assembly in water of end-functionalized polymers. For the first time, the Janus topology is not a result of the phase segregation of incompatible polymer arms, but is driven by the interactions between unsymmetrical and complementary hydrogen bonded stickers. It is therefore independent of the actual polymers used and works even for compatible polymers. To illustrate their applicative potential, we show that these Janus nanorods can efficiently stabilize oil-in-water emulsions.