Morphologies of star-block copolymers in dilute solutions

Area of Science:

• Polymer Chemistry
• Materials Science
• Computational Chemistry

Background:

• Star-block copolymers are complex macromolecules with unique architectural properties.
• Understanding their self-assembly in selective solvents is crucial for designing advanced materials.
• Previous studies have explored linear and branched block copolymers, but star-block systems present distinct challenges.

Purpose of the Study:

• To investigate the self-assembly morphologies of (AB)n and (BA)n star-block copolymers in a selective solvent.
• To elucidate the influence of molecular architecture and block interactions on micelle formation.
• To explore the formation of various supramolecular structures in concentrated solutions.

Main Methods:

• Dissipative particle dynamics (DPD) simulations were employed to model the behavior of star-block copolymers.
• Simulations were performed for individual molecules and multi-star solutions.
• System parameters, including arm number, block length, and solvent interactions, were systematically varied.

Main Results:

• (BA)n star-copolymers form unimolecular micelles with solvophobic B-cores and A-block coronas, exhibiting inter-molecular repulsion.
• (AB)n star-copolymers exhibit aggregative domains on their periphery, with domain number decreasing as B-block length or solvent repulsion increases.
• In multi-star solutions, diverse supramolecular morphologies arise, including connected-star aggregates, multicore micelles, segmented worms, and core-lump micelles, driven by molecular conformation.

Conclusions:

• The architecture of star-block copolymers significantly dictates their self-assembly behavior in selective solvents.
• The (BA)n and (AB)n architectures lead to distinct micellar formations and assembly characteristics.
• Molecular conformation plays a pivotal role in determining the macroscopic supramolecular structures formed by star-block copolymers in solution.