Metasurface-Enabled Holographic Lithography for Impact-Absorbing Nanoarchitected Sheets

Nanoarchitected materials represent a class of structural meta-materials that utilze nanoscale features to achieve unconventional material properties such as ultralow density and high energy absorption. A dearth of fabrication methods capable of producing architected materials with sub-micrometer resolution over large areas in a scalable manner exists. A fabrication technique is presented that employs holographic patterns generated by laser exposure of phase metasurface masks in negative-tone photoresists to produce 30-40 mu m-thick nanoarchitected sheets with 2.1 x 2.4 cm(2) lateral dimensions and approximate to 500 nm-wide struts organized in layered 3D brick-and-mortar-like patterns to result in approximate to 50-70% porosity. Nanoindentation arrays over the entire sample area reveal the out-of-plane elastic modulus to vary between 300 MPa and 4 GPa, with irrecoverable post-elastic material deformation commencing via individual nanostrut buckling, densification within layers, shearing along perturbation perimeter, and tensile cracking. Laser induced particle impact tests (LIPIT) indicate specific inelastic energy dissipation of 0.51-2.61 MJ kg(-1), which is comparable to other high impact energy absorbing composites and nanomaterials, such as Kevlar/poly(vinyl butyral) (PVB) composite, polystyrene, and pyrolized carbon nanolattices with 23% relative density. These results demonstrate that holographic lithography offers a promising platform for scalable manufacturing of nanoarchitected materials with impact resistant capabilities.

Automated summary

Nanoarchitected materials, with nanoscale features, exhibit unconventional properties such as ultralow density and high energy absorption. However, there is a lack of fabrication methods for producing these materials in a scalable manner. A new technique using holographic lithography with laser exposure is presented, allowing for the manufacturing of nanoarchitected materials with impact resistant capabilities. Experimental results demonstrate the potential of this method by producing nanoarchitected sheets with specific inelastic energy dissipation comparable to other high impact energy absorbing composites and nanomaterials.