Mesoscopic dynamics of complex vesicle formation: kinetic versus thermodynamic factors

Effects of the homopolymer molecular weight on a diblock copolymer in a 3D spherical confinement

The morphologies of a diblock copolymer spherically confined within a homopolymer were investigated by using the static self-consistent field theory method. A homogeneous A-B diblock copolymer sphere was surrounded by a homopolymer C. Upon changing the diblock volume fraction, homopolymer molecular weight and the interaction between the copolymer and its surrounding environment, different morphologies of the sphere were observed. Our calculations confirmed that when the homopolymer molecular weight was high a complete macrophase separation between the copolymer and the homopolymer was obtained. However, when the homopolymer molecular weight was low the homopolymer penetrated into the copolymer microdomains, diluting the diblock copolymer and reduced the interaction between the diblock copolymer segments and hence preventing them from segregating.

Soft confinement-induced morphologies of diblock copolymers

The self-assembly of diblock copolymers under soft confinement is studied systematically using a simulated annealing method applied to a lattice model of polymers. The soft confinement is realized by the formation of polymer droplets in a poor solvent environment. Multiple sequences of soft confinement-induced copolymer aggregates with different shapes and self-assembled internal morphologies are predicted as functions of solvent-polymer interaction and the monomer concentration. It is discovered that the self-assembled internal morphology of the aggregates is largely controlled by a competition between the bulk morphology of the copolymer and the solvent-polymer interaction, and the shape of the aggregates can be non-spherical when the internal morphology is anisotropic and the solvent-polymer interaction is weak. These results demonstrate that droplets of diblock copolymers formed in poor solvents can be used as a model system to study the self-assembly of copolymers under soft confinement.

Spontaneous formation of complex micelles from a homogeneous solution

We present an extensive computer simulation study of structure formation in amphiphilic block copolymer solutions after a quench from a homogeneous state. By using a mesoscopic field-based simulation method, we are able to access time scales in the range of a second. A "phase diagram" of final structures is mapped out as a function of the concentration and solvent philicity of the copolymers. A rich spectrum of structures is observed, ranging from spherical and rodlike micelles and vesicles to toroidal and net-cage micelles. The dynamical pathways leading to these structures are analyzed in detail, and possible ways to control the structures are discussed briefly.