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.