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Polymer Micelles with Hydrophobic Core and Ionic Amphiphilic Corona. 2. Starlike Distribution of Charged and Nonpolar Blocks in Coronaстатья
Статья опубликована в высокорейтинговом журнале
Информация о цитировании статьи получена из
Web of Science,
Scopus
Статья опубликована в журнале из списка Web of Science и/или Scopus
Дата последнего поиска статьи во внешних источниках: 18 июля 2013 г.
- Авторы: Lysenko Evgeny A., Kulebyakina Alevtina I., Chelushkin Pavel S., Rumyantsev Artem M., Kramarenko Elena Yu, Zezin Alexander B.
- Журнал: Langmuir
- Том: 28
- Год издания: 2012
- Издательство: American Chemical Society
- Местоположение издательства: United States
- Первая страница: 12663
- Последняя страница: 12670
- DOI: 10.1021/la302606a
- Аннотация: Hybrid polymer micelles with hydrophobic polystyrene (PS) core and ionic amphiphilic poly(4-vinylpyridine)/poly(N-ethyl-4-vinylpyridinium bromide) corona (P4VP/PEVP) spontaneously self-assembled from mixtures of PS-block-PEVP and PS-block-P4VP macromolecules in dimethylformamide/methanol/water selective solvent. The fraction of PEVP units in corona was b = [PEVP]/([PEVP]+[P4VP]) = 0.05 - 1.0. Micelles were transferred into pure water via dialysis technique and pH was adjusted to 9, where P4VP blocks are insoluble. Structural characteristics of micelles as function of corona composition were investigated. Methods of dynamic and static light scattering, electrophoretic mobility measurements, sedimentation velocity, transmission electron microscopy and UV-spectrophotometry were applied. Spherical morphology with core(PS) – shell(P4VP) – corona(PEVP) organization was postulated. Micelles demonstrated a remarkable inflection in structural characteristics near b ~ 0.5 - 0.7. Above this region aggregation number (m), core and corona radii of hybrid micelles coincided with those of individual PS-block-PEVP micelles. When b decreased below 0.5, dramatic growth of aggregation number was observed, accompanied by growth in micelle size and stretching PEVP chains. At b below 0.2 dispersions of hybrid micelles were unstable and easily precipitated upon addition of NaCl. Scaling relationships between micelle characteristics and b were obtained via minimization the micelle free energy, taking into account electrostatic, osmotic, volume and surface contributions. Theoretical estimations predicted dramatic influence of b on aggregation number, m ~ b^-3. This result is in general agreement with experimental data and confirms the correctness of the core – shell – corona model. The inflection in micelle characteristics entails drastic changes in micelle dispersion stability in the presence of oppositely charged polymeric (sodium polymethacrylate) or amphiphilic (sodium dodecylsulfate) complexing agents.
- Добавил в систему: Крамаренко Елена Юльевна