Crystallinity-driven morphological ripening processes for poly(ethylene oxide)-block-polycaprolactone micelles in...

Area of Science:

• Polymer Science
• Materials Science
• Supramolecular Chemistry

Background:

• Amphiphilic block copolymers self-assemble into various nanostructures.
• Poly(ethylene oxide)-block-polycaprolactone) (PEO-b-PCL) forms micelle-like spherical aggregates.
• The stability and transformation of these aggregates are crucial for their applications.

Purpose of the Study:

• To investigate the morphological transformations of PEO-b-PCL spherical aggregates.
• To understand the role of core crystallization in these transformations.
• To characterize the kinetics of the sphere-to-rod transition.

Main Methods:

• Self-assembly of PEO-b-PCL copolymer chains.
• Transmission electron microscopy (TEM) for morphological analysis.
• Dynamic light scattering (DLS) for aggregate size and stability assessment.

Main Results:

• Reproducible formation of spherical micelle-like aggregates.
• Observation of a slow transformation of spheres into rod-like or ribbon-like structures in deionized water.
• Rapid formation of individual rods from spheres once the transition initiates, with an absence of intermediate-length rods.

Conclusions:

• Core crystallization induces morphological changes in PEO-b-PCL aggregates.
• The sphere-to-rod transition is a complex process with distinct rapid and slow phases.
• Understanding these transformations is key for controlling PEO-b-PCL nanostructure morphology.