Intrinsically Thermally Degradable Microstructures Fabricated by Photodimerization in Rapid 3D Laser Printing

Classical photoresists utilized in direct laser writing (DLW) rely on photoinitiators and radical polymerization mechanisms to induce the cross-linking process. Herein, a simple initiator-free photoresist is introduced that enables the rapid fabrication of intrinsically thermally degradable 3D microstructures via DLW. The reported photoresist exploits the [2 + 2] photo-dimerization reaction of a multifunctional monosubstituted thiomaleimide compound while harvesting on-demand microstructure degradation through the intrinsic thermally reversible nature of the photocrosslinks. The photoresist exceeds attainable DLW printing speeds for non-chain growth resins, readily attaining 1500 µm s$^{−1}$ and up to 5000 µm s$^{−1}$, making it a promising system to compete with traditional photo-initiator containing resists while introducing on-demand post-printing degradability.