Direct observation of nanoparticle multiple-ring pattern formation during droplet evaporation with dark-field microscopy.
Controllable protocols towards nanoparticle self-assembly are important for applications of functional nanomaterials. Evaporation is a simple yet effective method to realize a gold nanoparticle ordered self-assembly, but until now, little attention has been paid to viewing the corresponding assembly process. Herein, with the help of dark-field microscopy, we in situ monitored the whole dynamic process of gold nanorod (GNR) assembly as the solvent evaporated. Differently from the previous coffee-ring effect, rod-shaped hydrophilic GNRs, within certain concentrations, spontaneously assembled into a multiple-ring pattern on a hydrophobic substrate via droplet drying. The self-assembly mechanism is consistent with a diffusion-driven kinetics, and the influencing factors, including the GNR surface modification, the colloid concentration, the surface property of the substrate, and the shape of the nanoparticles, were systematically investigated.
State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China. yanhe2021@hnu.edu.cn.
Hui
H
Li
Hao
H
Luo
Zhen
Z
Zhang
Yongjun
Y
Li
Bin
B
Xiong
Chunyan
C
Qiao
Xuan
X
Cao
Tie
T
Wang
Yan
Y
He
Guangyin
G
Jing