Thiol–Yne Photocurable Isosorbide-Derived Networks: Formulation and 3D Printing

The present work reports for the first time thiol-yne photoresins prepared from novel alkyne derivatives of isosorbide and its epimers, isomannide and isoidide. Isosorbide was selected as a key biobased monomer for this study in consideration of its unique rigid V-shaped structure and peculiar reactivity, as well as for the growing interest in this cyclic sugar due to its numerous industrial applications in polymer science. Dialkyl carbonate chemistry was used for the preparation of dipropargyl derivatives of isosorbide and its epimers via alkoxycarbonylation reaction conducted under mild conditions using catalytic amounts of 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD). Dialkyne monomers were then employed to produce biobased thiol-yne photoresins, formulated using trimethylolpropane tris-(3-mercaptopropionate) as a trifunctional thiol. The photopolymerization behavior was investigated by real-time Fourier-transform infrared spectroscopy and differential scanning calorimetry (DSC) to assess conversion efficiency and reaction kinetics. The resulting networks were characterized by DSC and dynamic mechanical thermal analysis. Furthermore, residual thiol groups enabled surface modification with poly-(ethylene glycol) methacrylate (PEGMA) to enhance hydrophilicity, as confirmed by contact angle measurements. Finally, the optimized isosorbide-based network formulation was successfully printed by digital light processing, achieving accurate 3D-printed structures.