Supramolecularly Engineered Amphiphilic Macromolecules: Molecular Interaction Overrules Packing Parameters

Area of Science:

• Supramolecular Chemistry
• Polymer Science
• Materials Science

Background:

• Self-assembly of amphiphilic macromolecules is crucial for nanomaterial design.
• Morphology control in self-assembly is typically governed by the packing parameter.
• Supramolecular interactions offer an alternative pathway for directing assembly.

Purpose of the Study:

• To investigate molecular interaction-driven self-assembly of supramolecularly engineered amphiphilic macromolecules (SEAMs).
• To demonstrate how specific supramolecular structure-directing units (SSDUs) influence self-assembled morphology.
• To explore the role of directional molecular interactions in overriding conventional packing parameter-dependent morphology control.

Main Methods:

• Synthesis of SEAMs with a single SSDU comprising an H-bonding group and a naphthalene diimide chromophore.
• Characterization of self-assembled structures formed by P1-50 (hydrazide SSDU) and P2-50 (amide SSDU).
• Analysis of self-assembly behavior upon mixing P1-50 and P2-50, and variation of hydrophobic/hydrophilic balance.

Main Results:

• Two SEAMs with identical chemical structures and hydrophobic/hydrophilic balance formed distinct morphologies: polymersomes (P1-50) and cylindrical micelles (P2-50).
• The difference in self-assembled structure was attributed to the specific H-bonding group (hydrazide vs. amide) within the SSDU.
• P1-50 and P2-50 exhibited self-sorted assembly when mixed.
• Altering the hydrophobic/hydrophilic balance did not change the observed morphologies, confirming interaction-driven assembly.

Conclusions:

• Directional molecular interactions, mediated by the SSDU, are the primary drivers of SEAM self-assembly.
• This interaction-driven mechanism can override established packing parameter rules in morphology control.
• SEAMs offer a versatile platform for designing complex self-assembled nanostructures through tailored supramolecular interactions.