3D Superstructures Consisting of Intersecting Gold Lamellae Formed by a Micelle-Mediated Anisotropic Growth Approach

Abstract

3D superstructures (3DSs) have attracted increasing interest because of the collective synergistic effects of individual building units, but their customization relies on tedious multistep strategy or high-end nanofabrication technology. Herein, for the first time, a facile block copolymer micelle-mediated anisotropic growth approach is reported to fabricate gold 3DSs consisting of tunable and intersecting lamellae with sawtooth-like edges. The preparation of the 3DSs depends on the mediation of reduction kinetics of gold precursors and adsorption of block copolymer micelles on gold crystal surfaces using disulfiram as ligands. The thickness of lamellae in the 3DSs is controllable from ≈21 to 102 nm by adjusting the weight fraction of the micellar hydrophobicity blocks and the composed lamellar number is regulated from ≈3 to ≈30. Additional morphologies, such as a dendritic mesoporous structure and meatball-like shapes, are obtained through controlling the extent of micelle swelling. Finite-difference time-domain simulations demonstrate that the unique 3DSs of gold lamellae with sawtooth-like edges form abundant hotspots giving rise to surface-enhanced Raman scattering (SERS). The 3DSs exhibit strong electromagnetic field enhancement and excellent performance as SERS substrates for detecting 4-mercaptobenzoic acid.