Temperature-Regulated Fluorescence and Association of an Oligo(ethyleneglycol)methacrylate-Based Copolymer with a Conjugated Polyelectrolyte鈥擳he Effect of Solution Ionic Strength
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- 作者：Sahika Inal ; Leonardo Chiappisi ; Jonas D. K枚lsch ; Mario Kraft ; Marie-Sousai Appavou ; Ullrich Scherf ; Manfred Wagner ; Michael Ryan Hansen ; Michael Gradzielski ; Andr茅 Laschewsky ; Dieter Neher
- 刊名：Journal of Physical Chemistry B
- 出版年：2013
- 出版时间：November 21, 2013
- 年：2013
- 卷：117
- 期：46
- 页码：14576-14587
- 全文大小：557K
- 年卷期：v.117,no.46(November 21, 2013)
- ISSN：1520-5207
文摘
Aqueous mixtures of a dye-labeled non-ionic thermoresponsive copolymer and a conjugated cationic polyelectrolyte are shown to exhibit characteristic changes in fluorescence properties in response to temperature and to the presence of salts, enabling a double-stimuli responsiveness. In such mixtures at room temperature, i.e., well below the lower critical solution temperature (LCST), the emission of the dye is strongly quenched due to energy transfer to the polycation, pointing to supramolecular interactions between the two macromolecules. Increasing the concentration of salts weakens the interpolymer interactions, the extent of which is simultaneously monitored from the change in the relative emission intensity of the components. When the mixture is heated above its LCST, the transfer efficiency is significantly reduced, signaling a structural reorganization process, however, surprisingly only if the mixture contains salt ions. To elucidate the reasons behind such thermo- and ion-sensitive fluorescence characteristics, we investigate the effect of salts of alkali chlorides, in particular of NaCl, on the association behavior of these macromolecules before and after the polymer phase transition by a combination of UV鈥搗is, fluorescence, and 1H NMR spectroscopy with light scattering and small-angle neutron scattering measurements.