Sustainable glycerol-based reactive diluent alternatives to commercial ethylene glycol diacrylate (EGDA) and 2-hydroxyethyl methacrylate (HEMA) for additive manufacturing

Abstract

This work proposes an efficient production route to sustainable reactive diluents based on modified glycerol as an alternative to commercial compounds such as 2-hydroxyethyl methacrylate (HEMA) and ethylene glycol diacrylate (EGDA). The synthesis of methacrylated vegetable oil (MO) was performed through nucleophilic substitution catalyzed by an organic base (triethylamine). Glycerol monomethacrylate (MGLY) and glycerol trimethacrylate (TGLY) were produced by Fischer esterification. The structural cross-analysis included ¹H NMR, ESI-MS, and FT-IR. The rheological investigation of systems composed of 75 wt% MO and 25 wt% reactive diluent confirmed the diluting role of MGLY and TGLY. The TGLY-based system exhibited a competitive apparent viscosity at 30 °C (η_30°C = 590 mPa s) and a flow activation energy (E_a = 48.4 kJ mol⁻¹) comparable to those of commercial HEMA- and EGDA-based precursors. The testing specimens for DMA, TGA, and mechanical analysis were successfully fabricated using an mSLA 3D printer, confirming their utility for additive manufacturing. The TGLY-containing system outperformed all the investigated thermosets in the crosslinking density (ν_e = 15.5 kmol m⁻³), the storage modulus at 30 °C (E′ = 473 MPa), and the tensile and flexural moduli. Based on the results, synthesized compounds improved the rheological, thermo-mechanical, and mechanical properties of MO-based thermosets.