Interactions of a Hydrophobically Modified Polymer with Oppositely Charged Surfactants

Abstract

The interaction of a hydrophobically modified anionic polymer (PMAOVE) with a cationic surfactant (DTAB) was studied using a multi-technique approach: turbidity, surface tension, and viscosity measurements, as well as EPR (5-doxyl stearic acid) and fluorescence (pyrene) probe techniques were used. In the investigated pH range (4-10), the cationic surfactant headgroups interact with the anionic carboxylic groups of the polymer backbone. In addition, nonpolar interactions of the surfactant chains with the n-octyl chains of PMAOVE stabilize the PMAOVE-DTAB complexes. Charge neutralization of the anionic polymer by the cationic surfactant leads to precipitation of the PMAOVE-DTAB complex at a certain DTAB concentration range. Further addition of DTAB causes a charge reversal of the complex and, subsequently, resolubilization of the precipitate. At an acidic pH (pH = 4), a second precipitation was observed, which is probably caused by conformational changes in the PMAOVE-DTAB complex. This second precipitate can be resolubilized by further addition of surfactant. At a neutral and basic pH, this second precipitation is absent. EPR analysis indicates that the surfactants form an ordered structure at the extended polymer chain at a neutral and basic pH, whereas at an acidic pH, a less ordered surfactant layer is formed on the coiled polymer with more hydrophobic microdomains.

Study of the interaction between a diblock polyelectrolyte PDMA-b-PAA and a gemini surfactant 12-6-12 in basic media

“…The driving force for the decrease of the surface tension derives from the surface-active polymers adsorbed at the air/solution interface, and their interaction with surfactant as well. This result notably differs from the increase in surface tension observed in other surfactant/polyelectrolyte systems with macroscopic precipitations [8].…”

“…hydrophobicity, charge density, and the nature of the surfactant will actually bring remarkable differences to the mixed system containing ionic surfactant and polyelectrolyte [6,7]. A hydrophobically modified copolymer poly(maleic acid/octyl vinyl ether) (PMAOVE) was used by Deo et al [8] to investigate its interaction with cationic surfactant dodecyltrimethylammonium bromide (DTAB). It is indicated that the complex formation behavior in the hydrophobically modified PMAOVE/DTAB system is notably different from that in mixed systems containing DTAB and nonmodified anionic polymer, since hydrophobic branches introduced into polymer backbone provide the additional hydrophobic force to keep the complexes stable.…”

Effect of cationic surfactant addition on the drag reduction behaviour of anionic polymer solutions

“…Most of the experimental efforts have shown that CAC is lower than the CMC of the surfactant (Goddard and Ananthapadmanabhan, 1993;Jonsson et al, 1998;Deo et al, 2007). This concentration is called critical aggregation concentration (CAC).…”

Drag reduction in turbulent pipeline flow of mixed nonionic polymer and cationic surfactant systems

“…The CAC is usually lower than the CMC (Goddard and Ananthapadmanabhan, 1993;Jonsson et al, 2003;Deo et al, 2007). The CAC is usually lower than the CMC (Goddard and Ananthapadmanabhan, 1993;Jonsson et al, 2003;Deo et al, 2007).…”