Polymer-surfactant-controlled 3D confined assembly of block copolymers for nanostructured colloidal particles

3D confined assembly in emulsion droplets is an effective way to prepare block copolymer particles with tunable nanostructures. In this process, the multi-component interaction at the droplet interface plays a crucial role, which is mainly dominated by surfactants. Here, we report the utilization of a polymer surfactant, ammonium-terminated polystyrene chains (N–PSn), to control the 3D confined assembly of poly(styrene-block-2-vinylpyridine) (PS-b-P2VP). N–PSn shows a different interfacial tuning ability from small molecular surfactants, which can not only stabilize the emulsion droplets but also increase the volume fraction of PS components through fusing its PS chains with PS-b-P2VP. Consequently, unusual nanostructured PS-b-P2VP particles were obtained based on a binary surfactant system of N–PSn and poly(vinyl alcohol), e.g., the rarely reported toroid-stacked ellipsoidal particles. The morphological formation mechanism was systemically studied by regulating the molecular weight of N–PSn. These results provide a new surfactant platform to tune the confined assembly of block copolymers.