Architecture-Dependent Interplay between Self-Assembly and Crystallization in Discrete Block Co-Oligomers

Area of Science:

• Polymer Science
• Materials Science
• Biomedical Engineering

Background:

• Self-assembly of block copolymers in water is crucial for developing stable nanostructures for biomedical applications.
• Control over nanostructure stability, morphology, and size is essential for these applications.
• Oligo(l-lactic acid)-b-oligo(ethylene glycol) block co-oligomers (BCOs) offer a platform for precise control over self-assembly.

Purpose of the Study:

• To investigate the self-assembly behavior of a library of sequence-controlled AB-type BCOs in water.
• To achieve predictable control over nanostructure morphology (vesicles, spherical micelles, cylindrical micelles) by varying the ratio of hydrophilic and hydrophobic blocks.
• To validate self-consistent field (SCF) predictions with experimental observations.

Main Methods:

• Synthesis of a library of fully discrete and sequence-controlled AB-type BCOs.
• Self-consistent field (SCF) computations to predict thermodynamic structures in water.
• Experimental characterization using calorimetry and scattering techniques to analyze formed morphologies.

Main Results:

• Excellent agreement was found between SCF-predicted and experimentally observed nanostructure morphologies.
• Calorimetry revealed crystallization of l-lactic acid (LLA) units within the lamellar-forming BCO bilayer.
• Crystallinity of LLA units did not impede the predicted bilayer thickness, indicating stable morphologies due to phase separation and crystallization.

Conclusions:

• SCF-guided design enables precise control over BCO self-assembly in water, leading to predictable and stable nanostructures.
• The combination of phase separation and crystallization in BCOs results in robust nanoparticle formulations.
• This approach facilitates the development of versatile nanostructures for advanced biomedical applications.