1 research outputs found
Mechanical Properties of Au Supracrystals Tuned by Flexible Ligand Interactions
Here mechanical properties of face
cubic centered colloidal crystals obtained out of equilibrium by solvent
evaporation of coated Au nanocrystals suspension, called supracrystals,
are reported as a function ligand chain length (<i>n</i>) and interparticle edge-to-edge distance within the supracrystals
(δ<sub>pp</sub>) for two nanocrystal sizes (<i>d</i>). Young’s modulus (<i>E</i>*) and hardness (<i>H</i>) are independent of δ<sub>pp</sub> and of the supracrystal
morphology. Both <i>E</i>* and <i>H</i> are in
the range of few tenths of a MPa to a few GPa. Tuning of δ<sub>pp</sub> by 50% is achieved by controlling the solvent vapor pressure
(<i>P</i><sub>t</sub>) during the evaporation process. For
any nanocrystal size, at <i>P</i><sub>t</sub> = 0, <i>E</i>* and <i>H</i> values markedly increase with
increasing <i>n</i> from 12 to 14. At <i>P</i><sub>t</sub> = 39% and 75%, such dependency disappears. This trend
differs from classical nanocomposite materials and is attributed to
a change in the conformation of flexible ligands with <i>n</i> and to free thiol-containing molecules trapped in the supracrystal
lattices