Polymer-micelle complexes viscosity

The principal goal of this paper is to examine the physical forces responsible for this latter type of polymer-surfactant micelle association. Since the formation of a polymer-micelle complex gives rise to gross conformational changes in the polymer molecule, a measurement of the solution viscosity provides the simplest means for monitoring polymer-micelle association. Here, the viscosity data on solutions containing polymer and surfactant of different molecular structures are used to explore the nature of polymer-miceUe complex formation. 

Figure 4. Influence of electrolyte NaCl concentration on the relative viscosity of solutions containing 1000 ppm polyethylene oxide and 8-phenyl hexadecane benzene sulfonate micelles. The polyelectrolyte type behavior of the polymer-micelle complex can be noted.

In the absence of interaction between polymer and surfactant there are three contributions in the relative viscosity of the solutions those from the polymer, the surfactant micelles and the surfactant monomers, respectively. The contribution of surfactant monomers is negligible, but that of micelles may be relatively significant, especially in case of low molecular mass polymers. In order to interpret the conformational change of the polymer during complex formation, a consequent choice of the reference medium is of primary importance. Referring to polymer-free surfactant solution is unsuitable, because the surfactant solution has a different composition as a solvent with and without polymer. In a 25 mmoLkg" aqueous NaDS solution the micelles result in a 4% increase in... 

The research on microemulsions currently concentrates on even more complex mixtures. By adding amphiphilic macromolecules the properties of microemulsions can be influenced quite significantly (see Chapter 4). If only small amounts of amphiphilic block copolymers are added to a bicontinuous microemulsion a dramatic enhancement of the solubilisation efficiency is found [27,28]. On the other hand, the addition of hydrophobically modified (HM) polymers to droplet microemulsions leads to a bridging of swollen micelles and an increase of the low shear viscosity by several orders of magnitude [29]. 

Binding ratios of SDS (BHD Ltd.) and CPC (Tokyo Kasei Ltd.) to HPC (M.W. =11 -I5xl0 Tokyo Kasei Ltd.) were determined at 30 °C by an equilibrium dialysis method. Cloud point of an HPC solution was observed by the naked eye. Amounts of p-dimethylaminoazobenzene (Nakarai Ltd.) solubilized by the surfactant micelle and the surfactant-polymer complex were determined at 30 °C by colorimetry at 1 = 418 nm. Viscosity was measured by an Ubbelohde-type capillary viscometer, a cone-plate rotary viscometer, or a Brookfield-type rotary viscometer at 25 or 30 °C. Mean diameter of secondary particles of kaolinite in its dilute suspension (1 g/dl) was estimated by a Coulter counter (type TA-II) in 154 mmol/dm NaCl at room temperature. 

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