Metamaterials from Plasma-Treated Block Copolymer Monolith

This study presents a streamlined methodology for fabricating gyroid-structured SiO₂ monoliths as dual-functional mechanical and optical metamaterials. By taking advantage of the self-assembly of polystyrene-block-polydimethylsiloxane (PS-b-PDMS), well-ordered gyroid thin films can be obtained through solvent vapor annealing. Subsequent oxygen plasma treatment simultaneously converts the PDMS nanonetwork into SiO₂ and decomposes the PS matrix, yielding a nanonetwork SiO₂ monolith while bypassing the complexity of conventional multistep templated synthesis. The resulting co-continuous architecture induces a fundamental transition from the intrinsic brittleness of SiO₂ to a ductile mechanical response, with an energy dissipation index of approximately 52.5% and significant deformation resilience under micro-compression, thereby demonstrating its characteristics as a mechanical metamaterial. Concurrently, the gyroid-structured SiO₂ exhibits enhanced visible-light transmittance owing to its high porosity and ultralow effective refractive index, reaching 95.2% for single-side coating and 97.0% for double-side coating on quartz substrates, highlighting its function as an optical metamaterial. As a proof of concept, the SiO₂ nanonetwork serves as a transparent protective overlayer for ITO conductive lines, enabling stable electrical resistance under compressive loading. This study provides a scalable route to multifunctional nanonetwork metamaterials that integrate mechanical durability with optical transparency, showing potential for applications in MEMS/NEMS, photonic devices, and semiconductor packaging.