Mechanical and Optical Properties of Nanocluster‐Silica Metamaterials

Nanostructured metamaterials with complex 3D geometries can be fabricated using two-photon lithography but are typically limited to specific materials by the available photoresists. Here, we develop a two-photon lithography photoresist for fabricating mechanically robust and optically active metamaterials. This photoresist consists of silver nanocluster photointiators in a polyhedral oligomeric silsequioxane (POSS) polymer matrix. Printed nanocomposites show a 216% increase in elastic modulus and 166% increase in energy absorption compared to structures made of POSS, while retaining 96% elastic recovery. Nanocomposite gyroid nanolattices reach 80% strain at failure. The nanolattice energy absorption is among the highest for lightweight nanoporous materials. Thermal annealing is used to convert the printed nanocomposites to nanoparticle-embedded glass with 54% higher energy absorption than fused silica. The annealed gyroid nanolattices contain silver nanoparticles and exhibit plasmonic activity. Right and left-handed chiral nanolattices result in different transmission spectra under linearly polarized light.