Gold-nanoparticle-infiltrated polystyrene inverse opals: A three-dimensional platform for generating combined optical properties

Photonic crystals incorporating metal nanoparticles have recently attracted increasing interest because they may open a way to generate novel optical properties. Although they provide an opportunity to manipulate combined optical signals, to date, optical properties of these composite materials have been scarcely investigated. Here, we present the first example of gold-nanoparticle-infiltrated polystyrene (GNIPS) inverse opals, which not only preserve localized surface plasmon resonance (LSPR) properties of gold nanoparticles (GNPs), but also replicate photonic features from templates. By varying the refractive index (RI) and the incident angle, the relative shifts between resonance peaks and diffraction peaks are observed. On the basis of the volatilization kinetics of ethanol within the GNIPS films, we investigate the external interactions of LSPR and photonic band gap (PBG). It is found that the LSPR peak of GNPs in GNIPS is unexpectedly red-shifted with the decrease of effective RI. Additionally, due to the reversible change of the two characteristic peaks, these GNIPS films exhibit an optical on-off switching capability, which is useful in monitoring the changes of the microenvironment by the permeation and release of surrounding media.