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| Volume 2, Issue 04 - 2006 |
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| 1 |
HYPERBRANCHED POLYTHIOETHERS: PREPARATION AND USE IN GOLD NANOPARTICLE COMPOSITE SENSOR FILMS |
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| Pages 109-120 |
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| OLIVER HIEN1A, HARTMUT KOMBER1, BRIGITTE I. VOIT1*, NADEJDA KRASTEVA2*, AKIO YASUDA2, TOBIAS VOSSMEYER2 |
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1 Leibniz Institut fuer Polymerforschung Dresden e.V., Hohe Strasse 6, D-01069 Dresden, Germany
1A present address: ASCALON Gesellschaft fuer Innovation in der Medizintechnik m.b.H., 01819 Kurort Berggiesshaebel
2 Materials Science Laboratory, Sony Deutschland GmbH, Hedelfingerstrasse 61, D-70327 Stuttgart, Germany
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| Received 18 January 2007 ; accepted 14 February 2007 |
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| Hyperbranched polythioethers were synthesized via radical mediated polyaddition reaction starting from 1,2-ethanedithiol or 1,3-propanedithiol (A) and 1-vinyloxy-2,2-bis(vinyloxymethyl)butane (B) via an A2 + B3 approach. Three types of terminal groups - unreacted thiols, unreacted double bonds and cyclic structures, were identified in the final products by NMR. The presence of the cyclic structures shifted the gel point in the A2 + B3 system to higher conversions and therefore, reduced the danger of crosslinking. The nature of the end groups was controlled by the feed ratio of the A and B monomers. The formation of free thiol groups was favoured when an excess of A functionality was employed. Thiol-terminated polymers were used as organic linker molecules for preparing Au-nanoparticle/hyperbranched polythioether (AuHP) composite chemiresistor sensors via layer-by-layer self-assembly. The UV/Vis spectra of the AuHP films showed a well-resolved plasmon absorbance band at about 550 nm, which evidences the presence of isolated Au-nanoclusters in the layer. The vapour sensing properties of the AuHP chemiresistors were characterized by measuring the change in their resistance when exposed to vapours of toluene, tetrachloroethylene (TCE), 1-propanol and water. All AuHP sensors responded with fast and reversible increase in resistance upon dosing with solvent vapours. The sensitivity to analytes decreased in the order toluene > TCE > 1-propanol > water. The chemical selectivity of the sensors reflects the expected hydrophobic nature of the hyperbranched polythioether linkers. |
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