Sustainable Acrylic-Isosorbide Polyurethane Resins for High-Resolution DLP 3D Printing

Digital light processing (DLP) three-dimensional (3D) printing requires resins that combine high resolution, mechanical integrity, and sustainability. Here, we present bio-based UV-curable acrylic-isosorbide polyurethane (A-IPU) resins synthesized from isosorbide-ethylene oxide (ISB-EO) diols and aliphatic diisocyanates, followed by acrylation with 2-hydroxyethyl methacrylate (2-HEMA). Four A-IPU resin series were synthesized with number-average molar masses (Mns) approximately 15,000 g/mol and narrow dispersities (Đ) (1.53–1.59). The formulations, prepared with polyethylene glycol 400 diacrylate (PEG400DA) and diphenyl(2,4,6-trimethylbenzoyl)phosphine oxide (TPO), exhibited viscosities below 400 mPa·s, suitable for DLP processing. Among the four systems, the ISB-10EO and 4,4′-methylene dicyclohexyl diisocyanate (H12MDI)-based A-IPU (A-IPU II) exhibited the best balance of properties, achieving a tensile strength of 5.47 MPa, elongation at break of 14.06%, Shore A hardness ≈ 90, and flexural strength of 1.58 MPa. Complex 3D structures, including tires, snowflakes, and flexible band-aids, were successfully fabricated with dimensional errors below 2%. The mechanical properties of A-IPU II fall within the range of petroleum-based acrylic-PU resins, confirming its practical competitiveness. Importantly, the near-solvent-free synthesis with quantifiable green metrics (PMI = 1.09, E-factor = 0.09, atom economy ≈ 100%) demonstrates the environmental advantages of this system.