%0 Journal Article %1 linford1998 %A Linford, Matthew R. %A Auch, Mark %A Mohwald, Helmuth %D 1998 %J Journal of the American Chemical Society %K lbl ph salt %N 1 %P 178-182 %R 10.1021/ja972133z %T Nonmonotonic Effect of Ionic Strength on Surface Dye Extraction during Dye Polyelectrolyte Multilayer Formation %U http://pubs.acs.org/doi/abs/10.1021/ja972133z %V 120 %X Multilayer formation between organic dyes and polyions is complicated by the possible competition between dye extraction from the surface by the polymer solution instead of polymer adsorption. We study the effects of salt concentration (NaCl, Na2SO4, MgCl2, and MgSO4) on this process and note that significant fractions of the dye are removed from the surface at intermediate salt concentration but that at lower or higher salt concentration less surface dye extraction occurs. Polymer solutions with intermediate NaCl concentrations show more than 60% dye extraction, while those of MgCl2, Na2SO4, and MgSO4 show approximately 30%, 25%, and 20% dye extraction, respectively. The maximum in dye extraction for all of these salts occurs when the solution Debye length is approximately 2 Å. The reduced efficiency of dye complexation away from the maximum is interpreted in terms of the polymer's expected increase in persistence length (low salt concentration) and the reduced electrostatic interactions between the charged dye and polymer (high salt concentration). The absorbance of poly(styrenesulfonate) remains roughly constant or slightly increases for the 1:1 and 2:2 salts but decreases with increasing 2:1 salt concentration. We propose that this decrease is due to charge reversal on the polymer or surface by the salt. Small shifts in dye peak positions suggest changes in the polarity of the surrounding matrix.

@article{linford1998, abstract = { Multilayer formation between organic dyes and polyions is complicated by the possible competition between dye extraction from the surface by the polymer solution instead of polymer adsorption. We study the effects of salt concentration (NaCl, Na2SO4, MgCl2, and MgSO4) on this process and note that significant fractions of the dye are removed from the surface at intermediate salt concentration but that at lower or higher salt concentration less surface dye extraction occurs. Polymer solutions with intermediate NaCl concentrations show more than 60% dye extraction, while those of MgCl2, Na2SO4, and MgSO4 show approximately 30%, 25%, and 20% dye extraction, respectively. The maximum in dye extraction for all of these salts occurs when the solution Debye length is approximately 2 Å. The reduced efficiency of dye complexation away from the maximum is interpreted in terms of the polymer's expected increase in persistence length (low salt concentration) and the reduced electrostatic interactions between the charged dye and polymer (high salt concentration). The absorbance of poly(styrenesulfonate) remains roughly constant or slightly increases for the 1:1 and 2:2 salts but decreases with increasing 2:1 salt concentration. We propose that this decrease is due to charge reversal on the polymer or surface by the salt. Small shifts in dye peak positions suggest changes in the polarity of the surrounding matrix. }, added-at = {2011-06-04T01:12:40.000+0200}, author = {Linford, Matthew R. and Auch, Mark and Mohwald, Helmuth}, biburl = {https://www.bibsonomy.org/bibtex/2c40d7991a3a2323510b1669554bad992/saghi}, description = {Nonmonotonic Effect of Ionic Strength on Surface Dye Extraction during Dye−Polyelectrolyte Multilayer Formation - Journal of the American Chemical Society (ACS Publications)}, doi = {10.1021/ja972133z}, eprint = {http://pubs.acs.org/doi/pdf/10.1021/ja972133z}, interhash = {19181287b88282f53ce28de4ace3974c}, intrahash = {c40d7991a3a2323510b1669554bad992}, journal = {Journal of the American Chemical Society}, keywords = {lbl ph salt}, number = 1, pages = {178-182}, timestamp = {2011-06-04T01:12:40.000+0200}, title = {Nonmonotonic Effect of Ionic Strength on Surface Dye Extraction during Dye Polyelectrolyte Multilayer Formation}, url = {http://pubs.acs.org/doi/abs/10.1021/ja972133z}, volume = 120, year = 1998 }