Additive-Driven Micellar Growth and Morphological Transitions in Tetronic Block Copolymers: Insights from...

Area of Science:

• Polymer Science
• Materials Chemistry
• Physical Chemistry

Background:

• Tetronics® block copolymers self-assemble into micelles.
• Additives can significantly influence micellar structure and properties.
• Understanding additive effects is crucial for controlling self-assembly.

Purpose of the Study:

• To investigate the impact of octanoic acid (OA) and perfluorooctanoic acid (PFOA) on Tetronics® T1304 and T1307 micellar behavior.
• To elucidate the mechanisms behind additive-induced structural modifications.
• To compare the effects of a common carboxylic acid versus a fluorinated analogue.

Main Methods:

• Cloud point (CP) and relative viscosity (ηrel) measurements.
• Small-angle neutron scattering (SANS), dynamic light scattering (DLS), and transmission electron microscopy (TEM).
• Pyrene fluorescence and density functional theory (DFT) calculations.

Main Results:

• OA induced micellar growth from spherical to ellipsoidal and vesicular structures in T1304, linked to PEO dehydration and PPO domain packing.
• PFOA caused minimal changes in micellar size and maintained spherical morphology.
• DFT indicated stronger Tetronics®-PFOA stabilization, but PFOA's rigidity limited its influence on micellar curvature.

Conclusions:

• Additive-induced dehydration and steric compatibility are key drivers of Tetronics® micellar structural evolution.
• Electronic affinity alone does not fully explain the observed structural changes.
• The distinct effects of OA and PFOA highlight the role of additive chemical structure in self-assembly.