Fabrication and Spatially Resolved Functionalization of 3D Microstructures via Multiphoton-Induced Diels-Alder Chemistry

Three-dimensional microstructures are fabricated utilizing direct laser writing combined with a non-radical step polymerization based on multiphoton-induced Diels-Alder chemistry of o-quinodimethanes and maleimides. Woodpile photonic crystals with a total of five axial periods and a rod spacing of down to 500 nm are fabricated. The structures are characterized via scanning electron microscopy and focused ion beam milling. In addition, corresponding photonic stop bands are investigated via light microscopy as well as transmission and reflection spectroscopy. The Diels-Alder based network formation during direct laser writing is verified via infrared spectroscopy. Spatially resolved surface patterning of covalently bonded functional molecules on fabricated structures is demonstrated by employing the direct laser writing setup and a bromine containing maleimide. The successful surface modification is verified via time-of-flight secondary ion mass spectrometry.