Induced growth of dendrite gold nanostructure by controlling self-assembly aggregation dynamics

Aggregation dynamics in gold nanoparticles can be controlled to produce self similar pattern. Controlling the reaction time of the nanoparticles during aggregation to reduce the Helmholtz free surface energy is the key parameter in this study. The study showed that the dynamics is dominated by the R...

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Bibliographic Details
Published in:Journal of colloid and interface science 2015-11, Vol.458, p.266-272
Main Authors: Abdellatif, M.H., Abdelrasoul, G.N., Scarpellini, A., Marras, S., Diaspro, A.
Format: Article
Language:English
Subjects:
Diffusion coefficient
Gold nanoparticles
Reaction limited aggregation
Self-assembly
XPS
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Summary:Aggregation dynamics in gold nanoparticles can be controlled to produce self similar pattern. Controlling the reaction time of the nanoparticles during aggregation to reduce the Helmholtz free surface energy is the key parameter in this study. The study showed that the dynamics is dominated by the Reaction Limited Aggregation Model (RLA) more than the Diffusion Limited Aggregation Model (DLA). Where the repulsion due to electrostatic force is dominant on the Van Der Walls attraction force, and the sticking probability of nanoparticles is low. The aggregation dynamics of AuNPs can be slowed down if the water evaporation of the drop casted colloidal AuNPs on a quartz substrate is slowed. Slowing down the evaporation allow the decrease in the electrostatic repulsion forces gradually, allowing the nanoparticles to sample all the possible orientation for the best thermodynamically favorable site. The lowest Helmholtz free surface energy for gold nanoparticles is corresponding to the dendrite fractal pattern. [Display omitted] Self-assembly of gold nanoparticles (AuNPs) is an important growth mode for fabricating functional materials. In this work we report a dendrite structure formed by slowing down the aggregation dynamics of AuNPs self-assembly. The obtained results show that the aggregation dynamics is dominated by the Reaction Limited Aggregation Model (RLA) more than the Diffusion Limited Aggregation Model (DLA). In which the repulsion due to electrostatic forces is dominant by the Van Der Walls attraction forces, and low sticking probability of nanoparticles. The aggregation dynamics of AuNPs can be slowed down if the water evaporation of the drop casted colloidal AuNPs on a quartz substrate is slowed. Slowing down the evaporation allows electrostatic repulsion forces to decrease gradually. At certain point, the attraction forces become higher than the electrostatic repulsion and hence cluster aggregation take place slowly. The slow aggregation dynamics allows the nanoparticles to sample all possible orientation in the sticking site, searching for the lowest energy configuration. The size distribution of the nanoparticles in liquid is confirmed using dynamic light scattering based on Stokes–Einstein equation for diffusion coefficient in water. X-ray and photoluminescence (PL) spectra of the sample after aggregation showed a shift which is related to the aggregation compared with non-aggregated colloidal nanoparticles in the solution. The study shows that
ISSN:0021-9797
1095-7103
DOI:10.1016/j.jcis.2015.07.055