Block Copolymer Nanocomposites under Soft Confinement.

Block copolymer (BCP) melts can be blended with solvents to self-assemble into complex droplets with internal structures. Controlling the morphology of these softly confined structures is crucial for various applications, including drug delivery. The addition of nanoparticles (NPs) to BCP droplets produces hierarchical co-assembly with intricate structures, where BCPs act as scaffolds. However, incorporating NPs can significantly alter the BCP droplet structure, leading to emergent behavior. Computer simulations reveal that confinement-induced frustration leads to a Janus-like morphology, with spatially segregated hexagonal and lamellar structures within the droplet bulk. Systematic exploration of NP loading and chemical interactions demonstrates various phase transitions, which are rationalized based on changes in the effective composition and solubility of the BCP droplet. A time-dependent model enables the study of the kinetics of several NP-induced layered morphologies, indicating that changes in the effective solubility of the BCP droplet result in a slow progression toward an onion morphology.