Schizophrenic Behavior of a Thermoresponsive Double Hydrophilic Diblock Copolymer at the Air-Water Interface
| Autor: | Rute, I., Romao, S., Beija, Mariana, Charreyre, Marie-Thérèse, Farinha, J. P. S., Gonçalves Da Silva, A.M., Martinho, J.M.G. |
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| Přispěvatelé: | De Loisy, Laure, Ingénierie des Matériaux Polymères - Laboratoire des Matériaux Macromoléculaires (IMP-LMM), Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut National des Sciences Appliquées de Lyon (INSA Lyon), Université de Lyon-Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Jean Monnet [Saint-Étienne] (UJM)-Centre National de la Recherche Scientifique (CNRS) |
| Jazyk: | angličtina |
| Rok vydání: | 2010 |
| Zdroj: | Langmuir Langmuir, American Chemical Society, 2010, 26 (3), pp.1807-1815 |
| ISSN: | 0743-7463 1520-5827 |
| Popis: | The thermoresponsive behavior of the rhodamine B end-labeled double hydrophilic block copolymer (DHBC) poly(N,N-dimethylacrylamide)-b-poly(N,N-diethylacrylamide) (RhB-PDMA207-b-PDEA177) and the 1:1 segmental mixture of PDEA and rhodamine B end-labeled PDMA homopolymers was studied over the range of 10-40°C at the air-water interface. The increase in collapse surface pressure (second plateau regime) of the DHBC with temperature confirms the thermoresponsiveness of PDEA at the interface. The sum of the π-A isotherms of the two single homopolymers weighted by composition closely follows the π-A isotherm of the DHBC, suggesting that the behavior of each block of the DHBC is not influenced by the presence of the other block. Langmuir-Blodgett monolayers of DHBC deposited on glass substrates were analyzed by laser scanning confocal fluorescence microscopy (LSCFM), showing schizophrenic behavior: at low temperature, the RhB-PDMA block dominates the inside of bright (core) microdomains, switching to the outside (shell) at temperatures above the lower critical solution temperature (LCST) of PDEA. This core-shell inversion triggered by the temperature increase was not detected in the homopolymer mixture. The present results suggest that both the covalent bond between the two blocks of the DHBC and the tendency of rhodamine B to aggregate play a role in the formation of the bright cores at low temperature whereas PDEA thermoaggregation is responsible for the formation of the dark cores above the LCST of PDEA. |
| Databáze: | OpenAIRE |
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