Morphological Diversity in Diblock Copolymer Solutions: A Molecular Dynamics Study

Coarse-grained molecular dynamics simulations that incorporate explicit water-mediated hydrophilic/hydrophobic interactions are employed to track spatiotemporal evolution of diblock copolymer aggregation in initially homogeneous solutions. A phase portrait the observed morphologies and their quantitative geometric features such as numbers, packing parameters, radial distribution functions solvent/monomers presented. Energetic entropic measures relevant self-assembly specific solvent accessible surface area (SASA) probability (pdfs) segmental stretch chains analyzed. The qualitatively capture experimentally morphological diversity Topologically simpler structures predicted include spherical micelles, vesicles (polymersomes), lamellae (bilayers), linear wormlike tori. More complex for larger chain lengths nearly symmetric compositions branched micelles with Y-shaped junctions cylindrical micelle networks. For concentrations, vesicle strands, held together by hydrogen bonds, “giant” composite aggregates consist lamellar, mixed hydrophobic/hydrophilic regions percolating water cores predicted. All dynamic exhibit diffuse domain boundaries. Morphology transitions across topologically can be rationalized based on SASA measurements. PDFs within vesicular assemblies appear follow a log-normal conducive maximizing configuration entropy.