Cross-linking of ROMP derived polymers using the two-photon induced thiol–ene reaction: towards the fabrication of 3D-polymer microstructures

Ring opening metathesis polymerization (ROMP) has become an important tool for the synthesis of highly defined polymers and various polymer architectures. In the present work, the residual double bonds in ROMP derived polymeric materials were exploited for a photoinduced thiol–ene reaction in order to achieve a selective cross-linking of the macromolecules. Besides the photoinduced thiol–ene reaction, which was investigated by means of FT-IR measurements, also the resulting change in the refractive index was studied by spectroscopic ellipsometry. To demonstrate the versatility of this reaction for the realization of 3D polymeric microstructures, films of poly(norbornene dicarboxylic acid, dimethylester) were structured via two-photon induced cross-linking. The accessibility and reactivity of the polynorbornene main chain CC double bonds in the thiol–ene reaction pave the way towards novel strategies for the realization of polymer 3D microstructures.