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Anionic Polymerization of an Amphiphilic Copolymer for Preparation of Block Copolymer Micelles Stabilized by π-π Stacking Interactions
Published on: October 10, 2016
pH-responsive diblock copolymer micelles at the silica/aqueous solution interface: Adsorption kinetics and
Kenichi Sakai1, Emelyn G Smith, Grant B Webber
1School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT, United Kingdom. k.sakai@leeds.ac.uk
The adsorption of pH-responsive poly(2-(dimethylamino)ethyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate) (PDMA-PDEA) copolymers onto silica depends on concentration and pH. Copolymers form micelles in alkaline solutions but remain dissolved in acidic solutions, affecting their adsorption behavior.
Area of Science:
- Polymer Science
- Surface Chemistry
- Materials Science
Background:
- Weakly basic diblock copolymers exhibit pH-responsive behavior.
- Understanding polymer adsorption at interfaces is crucial for material design.
Purpose of the Study:
- Investigate the adsorption of PDMA-PDEA copolymers at the silica/aqueous interface.
- Determine the influence of copolymer concentration and pH on adsorption.
- Characterize the structure and behavior of adsorbed polymer layers.
Main Methods:
- Quartz crystal microbalance with dissipation monitoring (QCM-D)
- Optical reflectometry
- Dynamic and static light scattering
Main Results:
- PDMA-PDEA copolymers form core-shell micelles above the critical micelle concentration (cmc) in alkaline solutions, but exist as unimers in acidic solutions.
- Adsorption is pH and concentration-dependent.
- Below cmc at pH 9, unimers adsorb flatly; above cmc, micelles influence adsorption, leading to thicker layers.
Conclusions:
- The adsorption mechanism of PDMA-PDEA copolymers on silica is governed by their solution state (unimer vs. micelle), which is dictated by pH and concentration.
- The adsorbed layer undergoes rearrangement and swelling, influenced by continued adsorption and hydration.
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Micelles
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