Vanillin-Derived Veratrole Reactive Diluents in Stereolithography

Abstract

We demonstrated the applicability of two vanillin-derived veratrole monomers, 4-vinyl veratrole (VV) and 3-allyl-5-vinyl veratrole (AVV), as reactive diluents for stereolithography (SLA). As structural analogues of styrene, these nonvolatile biobased monomers enable expanding the applications of styrenics to photocurable systems. Both monomers reduced the viscosity of a commercial oligomeric urethane acrylate resin to the levels acceptable for high-resolution SLA three-dimensional (3D) printing. Compared to two petrochemical controls, 2-phenoxyethyl acrylate and N-vinylpyrrolidone, the veratrole monomers required higher laser exposure to polymerize but allowed achieving high conversion of styrenic double bonds in the SLA process. Participation of the allyl group of AVV in polymerization increased the cross-link density of the 3D printed material, resulting in improved thermal stability and strength characteristics, whereas the VV-containing formulation yielded samples with superior ductility and toughness. Both vanillin-derived monomers demonstrated a significant advantage over 2-phenoxyethyl acrylate, a commercial aromatic diluent, in the thermomechanical properties of the printed materials. Furthermore, VV-based materials had higher elongation at break than the high-performing N-vinylpyrrolidone-containing formulation, whereas AVV showed superior Young’s modulus. We expect that the performance demonstrated by the veratrole monomers will accelerate the introduction of biobased styrenics into SLA resin formulations.