Interaction of Sodium Dodecyl Sulfate with Methacrylate−PEG Comb Copolymers

Williams, P. A.; Middleton, H.; English, R. J.; Broze, G.

Abstract

A series of sodium methacrylate and poly(ethylene glycol) (PEG) comb copolymers (MAA/PEG) with approximate PEG chain lengths of 7, 11, and 22 ethylene oxide units were synthesized by free radical polymerization. Their weight-average molecular mass was found to be ∼66 000. A commercial sample of a PEG comb polymer with an acrylic backbone was also used in the studies (Sokalan HP 80). The interaction of the MAA/PEG comb polymers and pure sodium methacrylate (SPMA) with sodium dodecyl sulfate (SDS) was studied by ESR spectroscopy using 5-doxyl stearic acid (5-DSA) spin probe and by conductivity measurements. Surfactant aggregation in water occurred at SDS concentrations lower than the surfactant critical micelle concentration (cmc) and depended on the polymer concentration. The observations have been attributed to changes in the effective ionic strength of the systems due to the polymer itself, and it has been concluded that there is no interaction between the MAA/PEG comb copolymers or SPMA and SDS. This has been confirmed by the fact that the decrease in surfactant aggregation concentration is similar in magnitude to the decrease observed on adding NaCl when counterion ion condensation effects are taken into account. It is apparent that the electrostatic repulsions between the surfactant molecules and the methacrylate backbone of the MAA/PEG comb copolymers inhibit association of SDS with the PEG side chains.

• Journal Article Type: Article
• Publication Date: Apr 30, 2005
• Deposit Date: Oct 26, 2016
• Journal: Langmuir
• Print ISSN: 0743-7463
• Electronic ISSN: 1520-5827
• Publisher: American Chemical Society
• Peer Reviewed: Peer Reviewed
• Volume: 21
• Issue: 11
• Pages: 5174-5178
• DOI: https://doi.org/10.1021/la040133o
• Keywords: sodium methacrylate, poly(ethylene glycol), comb copolymers (MAA/PEG),
• Public URL: http://researchrepository.napier.ac.uk/Output/315311