3D polymer microframes that exploit length-scale-dependent mechanical behavior

Abstract

The use of holographic interference lithography (IL) to create a 3D polymer microframe with a four-functional network geometry with sub-micrometer periodicity, low density, and 200 nm feature size was discussed. Such large area polymer/air structures were fabricated from negative Novolak resin photoresist and exhibited deformational characteristics due to their length-scale dependent mechanical behavior. The fabrication involved the interference of four laser beams and the transfer of the resultant intensity pattern into the photoresist through laser-assisted cationic polymerization. The 3D microstructures was an elongated IL variant of the classic Yablonovite photonic structure. Periodic microframe structures can direct crack propagation along certain crystallographic directions and also exhibit enhanced plastic response. Deformation mechanism characteristic of a nanoscale structure suggest a new way for creating a new ultralight, mechanically dissipative structures.