Hollow block copolymer nanoparticles through a spontaneous one-step structural reorganization

Area of Science:

• Materials Science
• Nanotechnology
• Polymer Chemistry

Background:

• Block copolymers (BCPs) self-assemble into various nanostructures.
• Controlling the internal morphology of BCP assemblies is challenging.
• Hollow nanostructures offer unique properties for encapsulation and delivery.

Purpose of the Study:

• To achieve spontaneous synthesis of hollow nanocages and nanotubes from BCP micelles.
• To investigate the structural reorganization process during sample drying.
• To explore the tunability of internal particle topology and its effect on dye loading.

Main Methods:

• Synthesis of poly(acrylic acid)-b-polylactide (P(AA)-b-P(LA)) block copolymers.
• Micelle formation and subsequent drying for structural reorganization.
• Transmission electron microscopy (TEM) and atomic force microscopy (AFM) for characterization.
• Stain-free imaging techniques to visualize hollow structures.

Main Results:

• Achieved one-step synthesis of hollow nanocages and nanotubes from P(AA)-b-P(LA) micelles via drying.
• Demonstrated that stain-free imaging is crucial for observing hollow nanostructures.
• Showed that drying conditions control internal topology, yielding solid or compartmentalized structures.
• Reorganized nanoparticles retained hollow structures upon resuspension.
• Observed significantly enhanced hydrophobic dye loading in reorganized nanoparticles compared to original structures.

Conclusions:

• Spontaneous formation of hollow nanostructures from BCPs is achievable through controlled drying.
• Internal morphology and properties of BCP assemblies can be tuned by manipulating drying conditions.
• Hollow P(AA)-b-P(LA) nanoparticles exhibit enhanced loading capacity for hydrophobic dyes, suggesting potential applications in drug delivery or encapsulation.