Multicore polymer micelles and aggregates are assemblies that contain several cores. The
dual-length-scale compartmentalized solvophobic–solvophilic molecular environment makes them
useful for, e.g., advanced drug delivery, high-precision synthesis platforms, confined catalysis, and
sensor device applications. However, designing and regulating polymer systems that self-assemble
to such morphologies remains a challenge. Using dissipative particle dynamics (DPD) simulations,
we demonstrate how simple, three-component linear polymer systems consisting of free solvophilic
and solvophobic homopolymers, and di-block copolymers, can self-assemble in solution to form
well-defined multicore assemblies. We examine the polymer property range over which multicore
assemblies can be expected and how the assemblies can be tuned both in terms of their morphology
and structure. For a fixed degree of polymerization, a certain level of hydrophobicity is required
for the solvophobic component to lead to formation of multicore assemblies. Additionally, the
transition from single-core to multicore requires a relatively high solvophobicity difference between
the solvophilic and solvophobic polymer components. Furthermore, if the solvophilic polymer
is replaced by a solvophobic species, well-defined multicore–multicompartment aggregates can
be obtained. The findings provide guidelines for multicore assemblies’ formation from simple
three-component systems and how to control polymer particle morphology and structure.