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Tunable diblock copolymer micelles-adapting behaviour via subtle chemical modifications.
Grant R Webber1, Erica J Wanless, Steven P Armes
1School of Process, Environmental and Materials Engineering, University of Leeds, Leeds LS2 9JT, UK. g.b.webber@leeds.ac.uk
Faraday Discussions
|January 22, 2005
Summary
Modifying poly(2-(dimethylamino)ethyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate) (PDMA-PDEA) copolymers by quaternisation alters micelle formation and adsorption. Higher quaternisation leads to smaller, more charged micelles and disordered adsorption layers, with acid-induced changes depending on the quaternisation degree.
Area of Science:
- Polymer Chemistry
- Surface Science
- Materials Science
Background:
- Poly(2-(dimethylamino)ethyl methacrylate)-block-poly(2-(diethylamino)ethyl methacrylate) (PDMA-PDEA) copolymers exhibit pH-dependent self-assembly into micelles.
- The quaternisation of the PDMA block is a key modification influencing copolymer properties.
Purpose of the Study:
- To investigate the effect of PDMA quaternisation degree on PDMA-PDEA copolymer solution and adsorption behavior.
- To understand the structural and morphological changes of adsorbed micelles upon acid treatment.
Main Methods:
- Synthesis of PDMA-PDEA copolymers with varying degrees of PDMA quaternisation.
- In situ atomic force microscopy (AFM) to study micelle adsorption on muscovite mica.
- Quartz crystal microbalance (QCM) to quantify adsorbed mass.
Main Results:
- Increasing PDMA quaternisation leads to smaller, more highly charged micelles and lower critical micellisation pH.
- Adsorbed micelle layers become more disordered with higher quaternisation.
- Surface-adsorbed micelles exhibit distinct responses to acid addition, ranging from reversible morphological changes to disruption, depending on quaternisation level.
- Adsorbed mass decreases with increasing quaternisation, confirmed by QCM.
Conclusions:
- The degree of PDMA quaternisation significantly controls the self-assembly, adsorption, and acid-responsive behavior of PDMA-PDEA copolymers.
- Electrostatic interactions play a crucial role in governing the observed phenomena.
- These findings offer insights into designing functional polymer materials for surface modification and responsive systems.