Green monomers for 3D printing: epoxy-methacrylate interpenetrating polymer networks as a versatile alternative for toughness enhancement in additive manufacturing

Abstract

Photopolymerization represents an environmentally friendly polymerization technique due to the ability of solvent-free and room-temperature curing. However, industrially used resins are usually derived from fossil resources, inherently increasing the environmental impact of such materials. Herein, the preparation of sequential interpenetrating polymer networks (IPNs) with a high content of renewable carbon by means of free radical photopolymerization and thermal epoxy curing was investigated in detail. Therefore, poly(ethylene glycol) dimethacrylate was used as UV-curable monomers, and resorcinol diglycidyl ether and trimethylolpropane were polymerized via step-growth polyaddition. Before the fabrication of IPNs, the networks were evaluated separately regarding their reactivity by means of (photo)-differential scanning calorimetry and real-time near-infrared photorheology. A combination of both networks resulted in IPNs with superior (thermo)mechanical properties and the ability to 3D-print complex shapes via stereolithography.