Self-assembly of Janus disks induced by small molecules in two-dimensional systems

We study the co-assembly of amphiphilic Janus disks and isotropic molecules by Monte Carlo simulations. A Janus particle is composed of two parts, one being attractive, A, and the other one being repulsive, R. Fluid molecules are strongly attracted by the R-sides and repelled by the A-sides. As the fluid density increases, the structure of the system changes from chaotically distributed Janus particles, through lamellar-like and gel-like structures, to the phase containing finite aggregates of Janus particles dispersed in the fluid. We show that "adsorption" of fluid molecules on the R-parts of Janus particles plays a key role in the co-assembly. The bond-switching between Janus particles is observed as the fluid density varies.