Harnessing disulfide and transesterification bond exchange reactions for recyclable and reprocessable 3D-printed vitrimers

Abstract

Two new vitrimeric materials have been studied for potential additive manufacturing applications such as 3D-printing. A monomer containing disulfide bonds and β-hydroxyesters was easily synthesized from two low-cost and commercially available reagents. Another disulfide-containing monomer was synthesized for comparison purposes. Materials were prepared through a UV-light radical polymerization of methacrylates. The addition of two reactive diluents such as poly(ethylene glycol) methyl ether methacrylate (PEGMA) and ethylene glycol phenyl ether methacrylate (EGPMA) was necessary to achieve a suitable viscosity for the curing as well as for their printability. The curing process was controlled by FTIR. Thermomechanical properties were investigated by means of DMTA analysis revealing near-ambient Tg values. Stress relaxation tests revealed that both materials were capable to relax the 63% of the initial stress in less than 10 min at 110 °C. The recyclability of the materials was achieved, and the mechanical and thermomechanical properties of the recycled samples were compared to the virgin ones revealing a great recovery of the initial properties. Finally, Digital Light Processing (DLP) technique was used to print complex structures with high resolution highlighting the great potential of these vitrimeric materials in 3D printing.