Phase separation and crystallization of binary nanoparticles induced by polymer brushes

The aggregation behaviors and phase separation of binary nanoparticles immersed in semiflexible polymer brushes are explored using molecular dynamics simulations. The conformations of the binary nanoparticle-brush mixtures are very sensitive to the size ratio q = sigma(l)/sigma(s) where sigma(l) and sigma(s) are the diameters for large and small nanoparticles, respectively, and the attractive interactions epsilon(M) between the nanoparticles and polymer brushes. The phase separation of the binary nanoparticles is observed at a relatively strong attractive interaction under the effects of inter-nanoparticle depletion attractions provided by polymer brushes. Furthermore, the crystallization of small nanoparticles occurs at a strong interaction and a hexagonal close-packed-like (hcp-like) ordered structure is formed. The present results may promise a new approach for controlling the self-assembling behavior of nanoparticles and constructing a better macroscopic performance of the material.