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Chemically Controlled Spatiotemporal Oscillations of Colloidal Assemblies
Author(s) -
Altemose Alicia,
SánchezFarrán María Antonieta,
Duan Wentao,
Schulz Steve,
Borhan Ali,
Crespi Vincent H.,
Sen Ayusman
Publication year - 2017
Publication title -
angewandte chemie international edition
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 5.831
H-Index - 550
eISSN - 1521-3773
pISSN - 1433-7851
DOI - 10.1002/anie.201703239
Subject(s) - chemical physics , oscillation (cell signaling) , cluster (spacecraft) , colloid , dispersion (optics) , materials science , hydrogen peroxide , suspension (topology) , electrolyte , colloidal particle , nanoparticle , chemical engineering , nanotechnology , chemistry , optics , physics , electrode , biochemistry , mathematics , organic chemistry , homotopy , computer science , pure mathematics , engineering , programming language
We report an autonomous oscillatory micromotor system in which active colloidal particles form clusters, the size of which changes periodically. The system consists of an aqueous suspension of silver orthophosphate microparticles under UV illumination, in the presence of varying concentrations of hydrogen peroxide. The colloid particles first attract each other to form clusters. After a short delay, these clusters abruptly disperse and oscillation begins, alternating between clustering and dispersion of particles. After a cluster oscillation initiates, the oscillatory wave propagates to nearby clusters and eventually all the clusters oscillate in phase‐shifted synchrony. The oscillatory behavior is governed by an electrolytic self‐diffusiophoretic mechanism which involves alternating electric fields generated by the competing reduction and oxidation of silver. The oscillation frequency is tuned by changing the concentration of hydrogen peroxide. The addition of inert silica particles to the system results in hierarchical sorting and packing of clusters. Densely packed Ag 3 PO 4 particles form a non‐oscillating core with an oscillating shell composed largely of silica microparticles.