Formation and assembly of amphiphilic Janus nanoparticles promoted by polymer interactions.

Almost three decades after de Gennes have introduced the term Janus for particles possessing two faces with different chemical nature, Janus particles are currently a hot topic in itself. Although de Gennes was not concerned with the size of particles, due to the advent and perspectives of nanotechnology, nanosized Janus particles have particularly received great attention. The capacity of having two antagonistic properties within the same particle has attracted interest on Janus nanoparticles for innumerous potential applications. It took some years for the studies about Janus nanoparticles to finally see great advances, mainly due to the progress in nanoparticle synthesis. What de Gennes might have not predicted (or at least he did not mention it during his speech) is that intermolecular interactions between polymers would be of immense importance to the actual achievement of Janus nanoparticles. Moreover, these interactions can also have large effects on the assembly process of amphiphilic Janus nanoparticles, which is important to form hierarchical structures and new materials at different scales. Hence, it is interesting to notice that de Gennes' contribution for the polymer field has been influencing the preparation and the controlled assembly of Janus nanoparticles. This article attempts to summarize empirical studies where noncovalent forces between polymers played a role, either on the production of Janus nanoparticles or on their assembly.