Formation of nanoparticle-block copolymer hybrids in competitive solvents

We investigate the encapsulation of polymer-tethered nanoparticles (NP) inside block copolymer (BCP) micelles, which turns to the mutual stabilization of BCP micelles and NPs by each other. It has been demonstrated, for the first time, that in the presence of co-solvent, which is selective for the core-forming block, the encapsulation of polymer-tethered NPs into the core of pre-formed BCP micelles is feasible. We find that in a certain range of cosolvent volume fraction, NP/BCP hybrid micelles comprising a single NP in micelle core are obtained. Significantly, in the presence of cosolvent the NP-loaded hybrid micelles remain intact, whereas the NP-free (empty) micelles undergo further transformations. In particular, our extensive molecular dynamics simualtions recognize mechanisms for the formation of NP/BCP hybrids, which include a one-by-one adsorption of individual BCP chains onto NP surface, fusion of NP with the pre-formed BCP micelles, or a combination of both mechanisms. The observations from numerical modelling are additionally supported by the results obtained from our experiments. The present work provide new opportunities for the fabrication of BCP-based hybrid nanomaterials having potential applications in drug delivery, diagnostics, catalysis, for energy harvesting materials, optical devices, etc.