Trioxanes as photodegradable motifs for additive manufacturing†

We introduce trioxanes as a new motif for on-demand photolysis of 3D printed polymer networks via an orthogonal light source using photoacid generators (PAGs). The acid-induced degradation of otherwise very stable trioxanes in combination with the versatility of generating trioxane-containing monomers makes the motif particularly interesting. Herein, we demonstrate the use of the motif as a trifunctional ene-crosslinker in combination with a trifunctional alicyclic thiol. Thereby, a latent PAG (UVI 6976, absorption ≤ 400 nm) is included into the photopolymerizable formulation and its latency during photocuring at longer wavelengths (≥400 nm) is proven. Upon photopolymerization, the PAG-containing material exhibits equal (thermo)mechanical performance to a reference network excluding PAG. Upon UV light irradiation, degradation of trixoanes is proven via NMR, DSC and solubility tests. Finally, facile printing of the trioxane-containing formulation has been shown.