| Autor: |
Carrascosa-Tejedor J; Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, U.K.; Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, Grenoble 38042, France., Tummino A; Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, Grenoble 38042, France.; CEA Commissariat à l'Energie Atomique et aux Energies Alternatives, 17 Rue des Martyrs, Grenoble Cedex 9 38054, France., Fehér B; Institute of Chemistry, Eötvös Loránd University, 112, Budapest H-1518, Hungary., Kardos A; Institute of Chemistry, Eötvös Loránd University, 112, Budapest H-1518, Hungary.; Department of Chemistry, Faculty of Education, J. Selye University, Komárno 945 01, Slovakia., Efstratiou M; Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, U.K., Skoda MWA; ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot OX11 0QX, U.K., Gutfreund P; Institut Laue-Langevin, 71 Avenue des Martyrs, CS20156, Grenoble 38042, France., Maestro A; Basque Foundation for Science, Plaza Euskadi 5, Bilbao 48009, Spain.; Centro de Fısica de Materiales (CSIC, UPV/EHU)─Materials Physics Center MPC, Paseo Manuel de Lardizabal 5, San Sebastián E-20018, Spain., Lawrence MJ; Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, U.K., Campbell RA; Division of Pharmacy and Optometry, Faculty of Biology, Medicine and Health, University of Manchester, Oxford Road, Manchester M13 9PT, U.K., Varga I; Institute of Chemistry, Eötvös Loránd University, 112, Budapest H-1518, Hungary.; Department of Chemistry, Faculty of Education, J. Selye University, Komárno 945 01, Slovakia. |
| Abstrakt: |
The interfacial structure and morphology of films spread from hyperbranched polyethylene imine/sodium dodecyl sulfate (PEI/SDS) aggregates at the air/water interface have been resolved for the first time with respect to polyelectrolyte charged density. A recently developed method to form efficient films from the dissociation of aggregates using a minimal quantity of materials is exploited as a step forward in enhancing understanding of the film properties with a view to their future use in technological applications. Interfacial techniques that resolve different time and length scales, namely, ellipsometry, Brewster angle microscopy, and neutron reflectometry, are used. Extended structures of both components are formed under a monolayer of the surfactant with bound polyelectrolytes upon film compression on subphases adjusted to pH 4 or 10, corresponding to high and low charge density of the polyelectrolyte, respectively. A rigid film is related to compact conformation of the PEI in the interfacial structure at pH 4, while it is observed that aggregates remain embedded in mobile films at pH 10. The ability to compact surfactants in the monolayer to the same extent as its maximum coverage in the absence of polyelectrolyte is distinct from the behavior observed for spread films involving linear polyelectrolytes, and intriguingly evidence points to the formation of extended structures over the full range of surface pressures. We conclude that the molecular architecture and charge density can be important parameters in controlling the structures and properties of spread polyelectrolyte/surfactant films, which holds relevance to a range of applications, such as those where PEI is used, including CO 2 capture, electronic devices, and gene transfection. |
