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Association between poly(vinylamine) and sodium dodecyl sulfate: Effects of mixing protocol, blending procedure, and salt concentration
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
KTH, School of Chemical Science and Engineering (CHE), Chemistry, Surface Chemistry.
2005 (English)In: Journal of Dispersion Science and Technology, ISSN 0193-2691, E-ISSN 1532-2351, Vol. 26, no 3, 329-340 p.Article in journal (Refereed) Published
Abstract [en]

The association between a weak cationic linear polyelectrolyte, poly(vinylamine), and the anionic surfactant sodium dodecyl sulfate (SDS) has been investigated in dilute solutions, containing 20 ppm of poly(vinylamine) and surfactant up to a concentration of 8 mM. We particularly focus on the importance of the order of addition of the components and of stirring after mixing. Two mixing protocols were used, denoted PTS and STP. In the PTS method the polyelectrolyte is added to the surfactant solution, and in the STP method the surfactant is added into the polyelectrolyte solution. The results obtained demonstrate the presence of long-lived trapped nonequilibrium states. In addition, we also address the effect of the blending procedure on association. We studied two blending methods, denoted Blending and Vigorous Blending. In the Blending method equal volumes of the polyelectrolyte and surfactant were added simultaneously to the sample tube, after which the ingredients were mixed together by turning the sample tube upside down a few times; in the Vigorous Blending method the mixing was provided by a magnetic stirrer. The results, obtained using turbidity, electrophoretic mobility, and light scattering measurements, demonstrate that Vigorous Blending facilitates flocculation at low SDS concentrations, close to the charge neutralization concentration of the system. This is interpreted as being due to additional surfactant incorporation in initially positively charged complexes during collision events. Vigorous mixing in excess surfactant produces stable dispersions consisting of small negatively charged complexes containing one polyelectrolyte and surfactant in excess of what is needed to neutralize the polyelectrolyte charges. The same results are obtained with the Blending protocol, which gives comparable particle size and polydispersity in excess surfactant and polyelectrolyte.

Place, publisher, year, edition, pages
2005. Vol. 26, no 3, 329-340 p.
Keyword [en]
polyelectrolyte, surfactant, polyelectrolyte-surfactant aggregate, polyelectrolyte-surfactant association, turbidity, electrophoretic mobility, dynamic light scattering, static light scattering, colloidal stability, nonequilibrium state, trapped state, charge neutralization concentration, particle size, polydispersity, surface forces, cationic polyelectrolyte, adsorption, layers, coadsorption, spectroscopy
URN: urn:nbn:se:kth:diva-14726DOI: 10.1081/dis-200049599ISI: 000228901400010ScopusID: 2-s2.0-18744416935OAI: diva2:332767
QC 20100525Available from: 2010-08-05 Created: 2010-08-05 Last updated: 2010-08-30Bibliographically approved
In thesis
1. Polyelectrolytes: Bottle-Brush Architectures and Association with Surfactants
Open this publication in new window or tab >>Polyelectrolytes: Bottle-Brush Architectures and Association with Surfactants
2008 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis has the dual purpose of raising awareness of the importance of the mixing protocol on the end products of polyelectrolyte-oppositely charged surfactant systems, and to contribute to a better understanding of the properties of bottle-brush polyelectrolytes when adsorbed onto interfaces.

In the first part of this thesis work, the effects of the mixing protocol and the mixing procedure on formed polyelectrolyte-oppositely charged surfactant aggregates were investigated. It was shown that the initial properties of the aggregates were highly dependent on the mixing parameters, and that the difference between the resulting aggregates persisted for long periods of time.

The second part of the studies was devoted to the surface properties of a series of bottle-brush polyelectrolytes made of charged segments and segments bearing poly(ethylene oxide) side chains; particular attention was paid to the effect of side chain to charge density ratio of the polyelectrolytes. It was shown that the adsorbed mass of the polyelectrolytes, and the corresponding number of poly(ethylene oxide) bearing segments at the interface, went through a maximum as the charge density of the polyelectrolyte was increased. Also, it was found that bottle-brush polyelectrolyte layers were desorbed quite easily when subjected to salt solutions. This observation was rationalized by the unfavourable excluded volume interactions between the side chains and the entropic penalty of confining them at an interface, which weaken the strength of the binding of the polyelectrolytes to the interface. However, it was shown that the same side chains effectively protect the adsorbed layer against desorption when the layer is exposed to solutions containing an oppositely charged surfactant. Investigation of the lubrication properties of the bottle-brush polyelectrolytes in an asymmetric (mica-silica) system also related the observed favourable frictional properties to the protective nature of the side chains. The decisive factor for achieving very low coefficients of friction was found to be the concentration of the side chains in the gap between the surfaces. Interestingly, it was shown that a brush-like conformation of the bottle-brush polyelectrolyte at the interface has little effect on achieving favourable lubrication properties. However, a brush-like conformation is vital for the resilience of the adsorbed layer against the competitive adsorption of species with a higher surface affinity.

Place, publisher, year, edition, pages
Stockholm: KTH, 2008. 39 p.
Trita-CHE-Report, ISSN 1654-1081 ; 2008:18
Polyelectrolyte, Surfactant, Bottle-Brush Polyelectrolyte, Comb Polyelectrolyte, Non-Equilibrium State, Polymer Architecture, Adsorption, Desorption, Association, Excluded Volume, Light Scattering, SFA, AFM, QCM-D, Turbidimeter, Mica, Silica, Surface Forces
National Category
Physical Chemistry
urn:nbn:se:kth:diva-4683 (URN)978-91-7178-903-7 (ISBN)
Public defence
2008-04-18, F3, Lindstedsvägen 28 100 44, Stockholm, 10:00
QC 20100830Available from: 2008-03-27 Created: 2008-03-27 Last updated: 2012-01-20Bibliographically approved

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