Structural interplay in block copolymer-bile salt complexes: from globules to ribbons.

Area of Science:

• Supramolecular Chemistry
• Polymer Science
• Materials Science

Background:

• Block copolymers and bile salts self-assemble into complex supramolecular structures.
• Understanding these structures is crucial for designing novel functional materials.

Purpose of the Study:

• To investigate supramolecular structures formed by poly(ethylene oxide)-block-poly(2-(trimethylammonium)ethyl methacrylate iodide) and sodium deoxycholate.
• To explore the influence of preparation protocols and temperature on aggregate morphology.

Main Methods:

• Dynamic Light Scattering (DLS)
• Small-Angle X-ray Scattering (SAXS)
• Cryogenic Transmission Electron Microscopy (Cryo-TEM)
• Proton Nuclear Magnetic Resonance (¹H NMR)

Main Results:

• Direct mixing yielded ribbons and globular particles; complex salt dispersion exclusively formed ordered ribbons.
• Globular particles are complex coacervate core micelles with a PTMAEMA core and PEO shell.
• Ribbon morphology arises from deoxycholate anion organization and block length limitations, representing the equilibrium structure at 25 °C.

Conclusions:

• Preparation protocols significantly impact block copolymer-bile salt aggregate morphology.
• Temperature influences the equilibrium between ribbon and globular structures.
• Findings provide strategies for designing and tuning aqueous block copolymer-bile salt aggregates.