Interfacial localization and voltage-tunable arrays of charged nanoparticles.
Experiments and computer simulations provide a new perspective that strong correlations of counterions with charged nanoparticles can influence the localization of nanoparticles at liquid-liquid interfaces and support the formation of voltage-tunable nanoparticle arrays. We show that ion condensation onto charged nanoparticles facilitates their transport from the aqueous-side of an interface between two immiscible electrolyte solutions to the organic-side, but contiguous to the interface. Counterion condensation onto the highly charged nanoparticles overcomes the electrostatic barrier presented by the low permittivity organic material, thus providing a mechanism to transport charged nanoparticles into organic phases with implications for the distribution of nanoparticles throughout the environment and within living organisms. After transport, the nanoparticles assemble into a two-dimensional (2D) nearly close-packed array on the organic side of the interface. Voltage-tunable counterion-mediated interactions between the nanoparticles are used to control the lattice spacing of the 2D array. Tunable nanoparticle arrays self-assembled at liquid interfaces are applicable to the development of electro-variable optical devices and active elements that control the physical and chemical properties of liquid interfaces on the nanoscale.
Department of Physics, University of Illinois at Chicago , Chicago, Illinois 60607, United States.
Mrinal K
MK
Bera
Henry
H
Chan
Daniel F
DF
Moyano
Hao
H
Yu
Sabina
S
Tatur
Daniel
D
Amoanu
Wei
W
Bu
Vincent M
VM
Rotello
Mati
M
Meron
Petr
P
Král
Binhua
B
Lin
Mark L
ML
Schlossman
charge-reversal; ion condensation; liquid−liquid interface; nanoparticles; transport; voltage-tunable array