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Hien, O. ; Komber, H. ; Voit, B. ; Krasteva, N. ; Yasuda, A. ; Vossmeyer, T.
Hyperbranched polythioethers: preparation and use in gold nanoparticle composite sensor films

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.

Quelle
Journal of Nanostructured Polymers and Nanocomposites 2

Seiten
109-120

DOI
http://www.jnpn.org/03,02,03.html

Erschienen am
June 2007
 
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