Two-photon Printing of Polymer Networks with Circular Dichroic Memory*

Metamaterial structures are fabricated with periodic length scales below incident light wavelengths, imparting properties that were not present in the bulk state such as negative Poisson ratio or negative refractive index. With an interest in further miniaturizing adaptive metamaterials, we hereby report on the high resolution, two-photon polymerization (2PP) of a thiol-vinyl shape-memory resin which exhibits shape-memory at the microscale. The glassy network is designed to have a trigger temperature (Tg) at 60 °C whereby it transforms into a rubbery network. These materials can be printed using 2PP at high resolution, with features beneath 500 nm, and are capable of being printed into a metamaterial lattice that displays circular dichroism. The metamaterial can be compressed and cooled to temporarily disrupt its metastructure and its corresponding circular dichroism.  Upon reheating, the original structure is recovered along with its circular dichoism. These results open the door to designing metastructures with interplay between mechanics and light.