Structure of a hydrophilic-hydrophobic block copolymer and its interactions with salt and an anionic surfactant

Wesley, Robin D, Dreiss, Cecile A, Cosgrove, Terence, Armes, Steven P, Thompson, Laurie, Baines, Fiona L and Billingham, Norman C (2005) Structure of a hydrophilic-hydrophobic block copolymer and its interactions with salt and an anionic surfactant. Langmuir, 21 (11). pp. 4856-4861.

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Abstract

The aggregation of a hydrophilic−hydrophobic diblock copolymer consisting of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) and poly(methyl methacrylate) (PMMA) in aqueous solution has been investigated by small-angle neutron scattering. This polybase is extensively protonated at low pH and forms micelles with a dense core of PMMA and a diffuse coronal layer of cationic PDMAEMA. Addition of salt induced micellar growth, brought about by charge screening and more efficient packing of the chains. As a result, the aggregation number increased from 8 up to 31. A similar effect was observed at low concentrations of an anionic surfactant, sodium dodecyl sulfate (SDS) since the net cationic charge in the hydrophilic coronal layer was reduced due to surfactant binding. However, at higher surfactant concentrations, a drastic structural reorganization occurred, as the PMMA became solubilized into the SDS micellar cores and the PDMAEMA chains interacted with the surfactant micelles, resulting in a “pearl-necklace” structure. The presence of the cationic polyelectrolyte significantly increased the population of SDS micelles by effectively lowering the critical micelle concentration of this anionic surfactant.

Item Type: Article
Schools and Departments: School of Life Sciences > Chemistry
Depositing User: Norman Billingham
Date Deposited: 06 Feb 2012 18:49
Last Modified: 30 Nov 2012 17:01
URI: http://sro.sussex.ac.uk/id/eprint/18455
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