Document Detail


Understanding Growth Kinetics of Nanorods in Microemulsion: A Combined Fluorescence Correlation Spectroscopy, Dynamic Light Scattering and Electron Microscopy Study.
MedLine Citation:
PMID:  23140268     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
Even though nanostructures of various shapes and sizes can be controlled by microemulsions, there is substantial difficulty in understanding their growth mechanism. The evolution of nanostructures from the time of mixing of reactants to their final stage is a heterogeneous process involving a variety of intermediates. To obtain a deeper insight into these kinetic steps, we studied the slow growth kinetics (extending over eight days) of iron oxalate nanorods inside the polar core of water-in-oil microemulsion droplets (MEDs) made of CTAB/1-butanol/isooctane. Fluorescence correlation spectroscopy (FCS), dynamic light scattering (DLS) and transmission electron microscopy (TEM), has been employed to monitor the nanostructure growth at (near) single droplet level and in an ensemble. Analyzing FCS data with suitable kinetic model we obtain transient dimer lifetime (28 s) and the droplet fusion rates (and fusion tendency) on each day as the reaction proceeds. The droplet fusion rate is found to directly control the nanorod growth in microemulsion solution and attains its maximum value (3.55  104 s-1) on day-6 when long nanorods are found in TEM data, implying that more and more reactants are fed into the growing system at this stage. Combining FCS, DLS and TEM results we find three distinct periods in the entire growth process a long nucleation-dominant nanoparticle growth period which form nanoparticles of critical (average) size of ~53 nm, followed by a short period where isotropic nanoparticles switch to anisotropic growth to form nanorods, and finally elongation of nanorods and growth (and shrinking) of nanoparticles is observed.
Authors:
Soma Sharma; Nibedita Pal; Pramit Kumar Chowdhury; Sobhan Sen; Ashok K Ganguli
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Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2012-11-12
Journal Detail:
Title:  Journal of the American Chemical Society     Volume:  -     ISSN:  1520-5126     ISO Abbreviation:  J. Am. Chem. Soc.     Publication Date:  2012 Nov 
Date Detail:
Created Date:  2012-11-12     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  7503056     Medline TA:  J Am Chem Soc     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
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