Designing polymersomes with surface-integrated nanoparticles through hierarchical phase separation

Abstract

Polymersomes with surface-integrated nanoparticles, in which a smaller sphere is attached to a larger capsule, are typically formed through complex processes like membrane deformation, polymerization, or membrane functionalization. This complexity restricts facile application of this unusual topology, for example in drug delivery or nanomotor science. Our study introduces a robust method for crafting polymersomes with surface-integrated nanoparticles using a hierarchical phase separation approach. By co-assembling block copolymers with aromatic aggregation-induced emission (AIE) moieties as side chains and photothermal-responsive guest molecules (PTM), spontaneous sequential phase separation processes occur that lead to their controlled formation. Polymer-rich liquid droplets form first, followed by internal phase separation of the guest molecules, which determines the formation of asymmetric morphology. This mechanism is elucidated in detail using liquid-phase transmission and cryogenic transmission electron microscopy (LP-TEM and cryo-TEM) and corroborated by theoretical simulations of the interaction forces between the block copolymers and guest molecules. Finally, the application potential of polymersomes with surface-integrated nanoparticles as nanomotors is demonstrated.