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Surface deposition and phase behavior of oppositely charged polyion-surfactant ion complexes. Delivery of silicone oil emulsions to hydrophobic and hydrophilic surfaces.

Clauzel M, Johnson ES, Nylander T, Panandiker RK, Sivik MR, Piculell L - ACS Appl Mater Interfaces (2011)

Bottom Line: The effect on the deposition of dilution of the bulk solution in contact with the surface was also investigated by gradual replacement of the bulk solution with 1 mM aqueous NaCl.The largest amount of deposited material after dilution was found for hydrophilic silica and for the least-hydrophobic cationic polymers.For the least-hydrophobic polyions, no significant codeposition of silicone oil was detected at hydrophobized silica after dilution if the initial SDS concentration was high.

View Article: PubMed Central - PubMed

Affiliation: Physical Chemistry, Kemicentrum, Lund University, Box 124, SE-221 00, Lund, Sweden. maryline.clauzel@gmail.com

ABSTRACT
The adsorption from mixed polyelectrolyte-surfactant solutions at hydrophobized silica surfaces was investigated by in situ -ellipsometry, and compared to similar measurements for hydrophilic silica surfaces. Three synthetic cationic copolymers of varying hydrophobicity and one cationic hydroxyethyl cellulose were compared in mixtures with the anionic surfactant sodium dodecylsulfate (SDS) in the absence or presence of a dilute silicone oil emulsion. The adsorption behavior was mapped while stepwise increasing the concentration of SDS to a polyelectrolyte solution of constant concentration. The effect on the deposition of dilution of the bulk solution in contact with the surface was also investigated by gradual replacement of the bulk solution with 1 mM aqueous NaCl. An adsorbed layer remained after complete exchange of the polyelectrolyte/surfactant solution for aqueous NaCl. In most cases, there was a codeposition of silicone oil droplets, if such droplets were present in the formulation before dilution. The overall features of the deposition were similar at hydrophobic and hydrophilic surfaces, but there were also notable differences. SDS molecules adsorbed selectively at the hydrophobized silica surface, but not at the hydrophilic silica, which influenced the coadsorption of the cationic polymers. The largest amount of deposited material after dilution was found for hydrophilic silica and for the least-hydrophobic cationic polymers. For the least-hydrophobic polyions, no significant codeposition of silicone oil was detected at hydrophobized silica after dilution if the initial SDS concentration was high.

No MeSH data available.


Related in: MedlinePlus

Evolution of layers adsorbed on hydrophilic silica from 100 ppm HPA/DMAM dissolved in 0.5 mM SDS, 1 mM NaCl subjected to different dilution procedures. The bulk solution was diluted directly with 1 mM NaCl (filled circles), or by sequential dilution with 0.5 mM SDS, 1 mM NaCl followed by 1 mM NaCl (open squares). The first dilution step defines t = 0.
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fig9: Evolution of layers adsorbed on hydrophilic silica from 100 ppm HPA/DMAM dissolved in 0.5 mM SDS, 1 mM NaCl subjected to different dilution procedures. The bulk solution was diluted directly with 1 mM NaCl (filled circles), or by sequential dilution with 0.5 mM SDS, 1 mM NaCl followed by 1 mM NaCl (open squares). The first dilution step defines t = 0.

Mentions: The results presented in Figures 7 and 8 show that a substantial deposition on a surface can be obtained from a polyelectrolyte–surfactant formulation initially at cmax, but that much, sometimes most, of the material layer will be removed on subsequent dilution with the pure aqueous sodium chloride solution. The removal is indeed predicted by maps of the adsorption behavior from experiments where the surfactant concentration is sequentially increased at constant polyelectrolyte concentration (Figure 3). From the latter behavior we would infer that the main reason for removal of the layer is that we lower the bulk surfactant concentration from cmax to effectively zero. On the other hand, we also observe (Figure 8) that the final deposition resulting from dilution is dependent on the initial surfactant concentration. This indicates a history-dependent deposition, where intermediate processes may trap complex at the surface before and during dilution. Based on these considerations, we chose to investigate formulations, with or without emulsion, of HPA/DMAM at cmax (= 0.5 mM SDS), and introduce a step where we diluted with a solution of 0.5 mM SDS and 1 mM NaCl before diluting with 1 mM NaCl. This means that we initially only diluted the polyelectrolyte in the bulk solution. Figure 9 illustrates the results obtained for an emulsion-free system and hydrophilic silica, where we also compare with the results for directly diluting with 1 mM NaCl. Clearly, diluting with 0.5 mM SDS removed much less material from the surfaces than rinsing with 1 mM NaCl. A subsequent dilution with 1 mM NaCl removed additional material from the surface, but the final adsorbed amount was higher than on directly diluting the bulk solution with 1 mM NaCl. The same protocol, with an intermediate dilution step with surfactant solution, was applied with and without added emulsion for both surfaces. We generally found (see the Supporting Information for details) that the intermediate dilution protocol gave rise to a significant increase in the final adsorbed amount after rinsing, especially for the formulation without added emulsion.


Surface deposition and phase behavior of oppositely charged polyion-surfactant ion complexes. Delivery of silicone oil emulsions to hydrophobic and hydrophilic surfaces.

Clauzel M, Johnson ES, Nylander T, Panandiker RK, Sivik MR, Piculell L - ACS Appl Mater Interfaces (2011)

Evolution of layers adsorbed on hydrophilic silica from 100 ppm HPA/DMAM dissolved in 0.5 mM SDS, 1 mM NaCl subjected to different dilution procedures. The bulk solution was diluted directly with 1 mM NaCl (filled circles), or by sequential dilution with 0.5 mM SDS, 1 mM NaCl followed by 1 mM NaCl (open squares). The first dilution step defines t = 0.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3211372&req=5

fig9: Evolution of layers adsorbed on hydrophilic silica from 100 ppm HPA/DMAM dissolved in 0.5 mM SDS, 1 mM NaCl subjected to different dilution procedures. The bulk solution was diluted directly with 1 mM NaCl (filled circles), or by sequential dilution with 0.5 mM SDS, 1 mM NaCl followed by 1 mM NaCl (open squares). The first dilution step defines t = 0.
Mentions: The results presented in Figures 7 and 8 show that a substantial deposition on a surface can be obtained from a polyelectrolyte–surfactant formulation initially at cmax, but that much, sometimes most, of the material layer will be removed on subsequent dilution with the pure aqueous sodium chloride solution. The removal is indeed predicted by maps of the adsorption behavior from experiments where the surfactant concentration is sequentially increased at constant polyelectrolyte concentration (Figure 3). From the latter behavior we would infer that the main reason for removal of the layer is that we lower the bulk surfactant concentration from cmax to effectively zero. On the other hand, we also observe (Figure 8) that the final deposition resulting from dilution is dependent on the initial surfactant concentration. This indicates a history-dependent deposition, where intermediate processes may trap complex at the surface before and during dilution. Based on these considerations, we chose to investigate formulations, with or without emulsion, of HPA/DMAM at cmax (= 0.5 mM SDS), and introduce a step where we diluted with a solution of 0.5 mM SDS and 1 mM NaCl before diluting with 1 mM NaCl. This means that we initially only diluted the polyelectrolyte in the bulk solution. Figure 9 illustrates the results obtained for an emulsion-free system and hydrophilic silica, where we also compare with the results for directly diluting with 1 mM NaCl. Clearly, diluting with 0.5 mM SDS removed much less material from the surfaces than rinsing with 1 mM NaCl. A subsequent dilution with 1 mM NaCl removed additional material from the surface, but the final adsorbed amount was higher than on directly diluting the bulk solution with 1 mM NaCl. The same protocol, with an intermediate dilution step with surfactant solution, was applied with and without added emulsion for both surfaces. We generally found (see the Supporting Information for details) that the intermediate dilution protocol gave rise to a significant increase in the final adsorbed amount after rinsing, especially for the formulation without added emulsion.

Bottom Line: The effect on the deposition of dilution of the bulk solution in contact with the surface was also investigated by gradual replacement of the bulk solution with 1 mM aqueous NaCl.The largest amount of deposited material after dilution was found for hydrophilic silica and for the least-hydrophobic cationic polymers.For the least-hydrophobic polyions, no significant codeposition of silicone oil was detected at hydrophobized silica after dilution if the initial SDS concentration was high.

View Article: PubMed Central - PubMed

Affiliation: Physical Chemistry, Kemicentrum, Lund University, Box 124, SE-221 00, Lund, Sweden. maryline.clauzel@gmail.com

ABSTRACT
The adsorption from mixed polyelectrolyte-surfactant solutions at hydrophobized silica surfaces was investigated by in situ -ellipsometry, and compared to similar measurements for hydrophilic silica surfaces. Three synthetic cationic copolymers of varying hydrophobicity and one cationic hydroxyethyl cellulose were compared in mixtures with the anionic surfactant sodium dodecylsulfate (SDS) in the absence or presence of a dilute silicone oil emulsion. The adsorption behavior was mapped while stepwise increasing the concentration of SDS to a polyelectrolyte solution of constant concentration. The effect on the deposition of dilution of the bulk solution in contact with the surface was also investigated by gradual replacement of the bulk solution with 1 mM aqueous NaCl. An adsorbed layer remained after complete exchange of the polyelectrolyte/surfactant solution for aqueous NaCl. In most cases, there was a codeposition of silicone oil droplets, if such droplets were present in the formulation before dilution. The overall features of the deposition were similar at hydrophobic and hydrophilic surfaces, but there were also notable differences. SDS molecules adsorbed selectively at the hydrophobized silica surface, but not at the hydrophilic silica, which influenced the coadsorption of the cationic polymers. The largest amount of deposited material after dilution was found for hydrophilic silica and for the least-hydrophobic cationic polymers. For the least-hydrophobic polyions, no significant codeposition of silicone oil was detected at hydrophobized silica after dilution if the initial SDS concentration was high.

No MeSH data available.


Related in: MedlinePlus