Digital Light Processing 3D Printing of Isosorbide- and Vanillin-Based Ester and Ester–Imine Thermosets: Structure–Property Recyclability Relationships

Abstract

Four isosorbide-based photocurable resins were designed to reveal correlations between the composition and chemical structure, digital light processing (DLP) three-dimensional (3D) printability, thermoset properties, and recyclability. Especially, the role of functional groups, i.e., the concentration of ester groups vs the combination of ester and imine functionalities, in the recyclability of the resins was investigated. The resins consisted of methacrylated isosorbide alone or in combination with methacrylated vanillin or a flexible methacrylated vanillin Schiff-base. The composition of the resins significantly affected their 3D printability as well as the physical and chemical properties of the resulting thermosets. The results indicated the potential of methacrylated isosorbide to confer rigidity to thermosets with some negative effects on the printing quality and solvent-resistance properties. An increase in the methacrylated vanillin concentration in the resin enabled us to overcome these drawbacks, leading, however, to thermosets with lower thermal stability. The replacement of methacrylated vanillin with the methacrylated Schiff-base resin decreased the rigidity of the networks, ensuring, on the other hand, improved solvent-resistance properties. The results highlighted an almost complete preservation of the elastic modulus after the reprocessing or chemical recycling of the ester–imine thermosets, thanks to the presence of two distinct dynamic covalent bonds in the network; however, the concentration of the ester functions in the ester thermosets played a significant role in the success of the chemical recycling procedure.

Sustainable Vat Photopolymerization‐Based 3D‐Printing through Dynamic Covalent Network Photopolymers

“…Liguori and her research team have introduced a novel material involving isosorbide-based resins and thermosets. [23] The materials employed comprise methacrylated isosorbide, methacrylated vanillin, and Schiff-base resin. The Schiff-base resin is derived from 2,2'-(ethylenedioxy)-bis(ethylamine) through an imination reaction with the methacrylated vanillin monomer.…”

Designed to Degrade: Tailoring Polyesters for Circularity

“…The synergistic effect of ester and imine functions to facilitate the chemical recyclability was recently demonstrated . A resin was composed of 50 wt % methacrylated isosorbide monomer and 50 wt % methacrylated vanillin Schiff base monomer.…”