An improved convective self-assembly method for the fabrication of binary colloidal crystals and inverse structures.
We report an improved convective self-assembly method for the fabrication of highly ordered, crack-free binary colloidal crystals (BCCs) and the associated inverse structures in large domains at length scales of several centimeters. With this method, BCCs can be fabricated in a non-close packed pattern and binary inverse opal films can be obtained over a centimeter scale. The presence of tetraethyl orthosilicate (TEOS) sol in the self-assembly system was found to play a significant role in the resultant structures. The pseudostop band positions are adjustable via varying the number ratio of small to large polystyrene (PS) spheres. At a given TEOS-to-PS ratio, the binary inverse opal film thickness was controllable by varying the colloidal volume fraction with an upper thickness threshold (>16 layers).
Department of Chemical and Biomolecular Engineering, National University of Singapore, Singapore 117576, Singapore.
Zhongyu
Z
Cai
Jinghua
J
Teng
Yong
Y
Wan
X S
XS
Zhao