Surface-Adsorbed Nanodroplets of Symmetric Diblock Copolymers Have Versatile and Stimuli-Responsive Nanostructure

The structure of block copolymer nanodroplets adsorbed on a surface is currently understudied despite them being a key component of hierarchically organized tunable nanostructured coatings. In this work, we discovered that the surface-adsorbed nanodroplets of symmetric diblock copolymers possess a variety of unique equilibrium nanostructures. One can realize the transitions between these morphologies by tuning the interaction parameters between the components (polymer, solvent, and surface), which can be done experimentally by adding surfactants or tuning temperature and pH. We observed this responsiveness and versatility of structures and transitions between them for small nanodroplets (with size of tens of nanometers). We obtained comprehensive equilibrium diagrams of states by performing large-scale self-consistent field theory calculations according to a recently developed algorithm that does not require prior knowledge of potential equilibrium structures. We showed that the simplest symmetric diblock copolymers are able to form versatile nanostructures on a surface when confined to a droplet. This, in turn, provides the opportunity for preparing hierarchically organized surfaces with tunable nanopatterning simply and controllably.