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Using Polystyrene-block-poly(acrylic acid)-coated Metal Nanoparticles as Monomers for Their Homo- and Co-polymerization
Published on: July 9, 2015
Temperature-induced reversible morphological changes of polystyrene-block-poly(ethylene oxide) micelles in solution
Prachur Bhargava1, Yingfeng Tu, Joseph X Zheng
1The Maurice Morton Institute and Department of Polymer Science, The University of Akron, Akron, Ohio 44325-3909, USA.
Temperature changes reversibly alter polystyrene-block-poly(ethylene oxide) micelle shapes, transitioning from vesicles to spheres. These reversible morphological changes in DMF/water systems are crucial for material science applications.
Area of Science:
- Polymer Science
- Materials Science
- Supramolecular Chemistry
Background:
- Polystyrene-block-poly(ethylene oxide) (PS-b-PEO) copolymers form micelles in selective solvents.
- Understanding temperature-dependent morphology is key for advanced material design.
- Solvent composition significantly influences self-assembly behavior.
Purpose of the Study:
- To investigate temperature-induced reversible morphological transitions of PS962-b-PEO227 micelles in DMF/water.
- To determine the critical temperatures for micellization and morphological changes.
- To elucidate the driving forces behind these reversible transformations.
Main Methods:
- Transmission electron microscopy (TEM) for direct visualization of micelle morphology.
- Dynamic light scattering (DLS) to measure hydrodynamic radius changes.
- Turbidity measurements to determine critical transition temperatures.
- Static light scattering (SLS) to complement DLS findings.
Main Results:
- Micelle morphology transitioned from vesicles to worm-like cylinders and spheres with increasing temperature.
- Morphological changes were fully reversible upon cooling, with no observed hysteresis.
- Hydrodynamic radius decreased with increasing temperature, consistent with morphological shifts.
- Critical transition temperatures depended on copolymer and water concentrations.
Conclusions:
- Temperature reversibly controls PS-b-PEO micelle morphology in DMF/water systems.
- Morphological transitions are driven by changes in corona and interface free energies.
- Low water concentration is essential for observing these temperature-dependent morphological changes.
- Large compound micelles can act as intermediates during morphological pathway transitions.
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