Tunable anisotropy in inverse opals and emerging optical properties

Phillips, K.R., Vogel, N., Hu, Y., Kolle, M., Perry, C.C. ORCID: 0000-0003-1517-468X and Aizenberg, J., 2014. Tunable anisotropy in inverse opals and emerging optical properties. Chemistry of Materials, 26 (4), pp. 1622-1628. ISSN 0897-4756

[img]
Preview
Text
216352_PubSub1752_Perry_main.pdf

Download (1MB) | Preview

Abstract

Using self-assembly, nanoscale materials can be fabricated from the bottom up. Opals and inverse opals are examples of self-assembled nanomaterials made from crystallizing colloidal particles. As self-assembly requires a high level of control, it is challenging to use building blocks with anisotropic geometry to form complex opals, which limits the realizable structures. Typically, spherical colloids are employed as building blocks, leading to symmetric, isotropic superstructures. However, a significantly richer palette of directionally dependent properties are expected if less symmetric, anisotropic structures can be created, especially originating from the assembly of regular, spherical particles. Here we show a simple method to introduce anisotropy into inverse opals by subjecting them to a post-assembly thermal treatment that results in directional shrinkage of the silica matrix caused by condensation of partially hydrated sol-gel silica structures. In this way, we can tailor the shape of the pores, and the anisotropy of the final inverse opal preserves the order and uniformity of the self-assembled structure, while completely avoiding the need to synthesize complex oval-shaped particles and crystallize them into such target geometries. Detailed X-ray photoelectron spectroscopy (XPS) and infrared (IR) spectroscopy studies clearly identify increasing degrees of sol-gel condensation in confinement as a mechanism for the structure change. A computer simulation of structure changes resulting from the condensation-induced shrinkage further confirmed this mechanism. As an example of property changes induced by the introduction of anisotropy, we characterized the optical spectra of the anisotropic inverse opals and found that the optical properties can be controlled in a precise way using calcination temperature.

Item Type: Journal article
Alternative Title: Supplemental information for tunable anisotropy in inverse opals and emerging optical properties
Publication Title: Chemistry of Materials
Creators: Phillips, K.R., Vogel, N., Hu, Y., Kolle, M., Perry, C.C. and Aizenberg, J.
Publisher: American Chemical Society
Date: 2014
Volume: 26
Number: 4
ISSN: 0897-4756
Identifiers:
NumberType
10.1021/cm403812yDOI
Divisions: Schools > School of Science and Technology
Depositing User: EPrints Services
Date Added: 09 Oct 2015 10:39
Last Modified: 09 Jun 2017 13:35
URI: http://irep.ntu.ac.uk/id/eprint/16170

Actions (login required)

Edit View Edit View

Views

Views per month over past year

Downloads

Downloads per month over past year