Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
9694255 | Thermochimica Acta | 2005 | 6 Pages |
Abstract
We describe phase transitions in microfilm assemblies of octanethiol (OT)-capped 2-4 nm-diameter Ag nanoclusters prepared from solutions with OT/Ag+ ratios of â¼50. Using DSC we observe two melting/crystallization-type reversible phase transitions: one at â¼61 °C due to interdigiated unattached octanethiol, and the other at â¼125 °C due to the phase comprised of the assembly of OT-capped nanoclusters. Increased thermal fluctuations weaken the inter-chain hydrophobic interactions between interdigitated OT molecules, leading to both phase transitions. The thiolate bond of OT-molecules bound to Ag nanoclusters are more rigid, thereby requiring a higher temperature to increase the flexibility of the alkyl chain of OT, and to melt the nanocluster assembly. The mobility of the nanoclusters in the melt is limited, and morphological features of the original assemblies are retained during recrystallization. No observable mass loss is detected up to â¼180 °C, above which OT molecules desorb from the Ag nanoclusters.
Related Topics
Physical Sciences and Engineering
Chemical Engineering
Fluid Flow and Transfer Processes
Authors
A.V. Ellis, J. D'Arcy-Gall, K. Vijayamohanan, R. Goswami, P.G. Ganesan, C. Ryu, G. Ramanath,