Unexpected toroidal micelles formed from St/MMA gradient copolymers.

Area of Science:

• Polymer Science
• Materials Chemistry
• Supramolecular Chemistry

Background:

• Toroidal micelles are rarely observed in gradient copolymer systems.
• Understanding their formation is key to controlling self-assembly.

Purpose of the Study:

• To report the formation of massive toroidal micelles from styrene/methyl methacrylate gradient copolymers.
• To investigate the influence of thermal treatment on micelle morphology.

Main Methods:

• Utilized a common solvent mixing method.
• Implemented a specific cooling-heating procedure for self-assembly.
• Investigated morphology changes under different thermal protocols.

Main Results:

• Massive toroidal micelles were successfully formed from styrene (St)/methyl methacrylate (MMA) gradient copolymers.
• Spherical micelles were obtained initially via solvent mixing.
• A cooling-heating process transformed spherical micelles into toroidal structures via vesicles.
• A reverse heating-cooling process did not yield toroidal micelles.

Conclusions:

• The study introduces new members to the family of toroidal micelles.
• Demonstrates that the heat treatment procedure critically dominates the morphology of gradient copolymer micelles.
• Reveals pathway-dependent self-assembly behavior in copolymer systems.