Triblock Copolymer Vesicle Morphogenesis

Scientific question

How do initially dispersed amphiphilic BAB triblock copolymers reorganize into a closed vesicle, and what molecular changes accompany each transition along the pathway?

Approach

We used coarse-grained molecular dynamics with explicit aqueous solvent and MARTINI-based interactions to follow self-assembly from randomly distributed polymers. The analysis connected aggregate morphology with aggregation number, hydrophobic contact with solvent, and polymer end-to-end distance distributions.

Main published findings

• Vesiculation proceeds through an interconnected aggregate network, a cage of cylindrical micelles, and a lamellar cage before the membrane closes.
• The cage-to-vesicle transition occurs at essentially constant aggregation number while nearly eliminating contact between the hydrophobic B blocks and the solvent.
• Folded chain conformations are common both for isolated polymers and for polymers within the vesicle. The end-to-end distance distribution becomes broader inside the vesicular bilayer.
• Increasing B-block hydrophobicity shortens the vesiculation time without qualitatively changing the self-assembly pathway.

Why it matters

The study provides a molecular-level picture of how hydrophobic interactions, chain conformations, and collective packing changes produce a closed polymer vesicle.

Read the peer-reviewed article