Copolymerizing Lignin for Tuned Properties of 3D-Printed PEG-Based Photopolymers

The global emphasis on environmental conservation has sparked the exploration for alternative materials to replace nonrenewable petroleum-based products. With abundant lignocellulosic biomass, there is a growing focus on designing biobased polymers with enhanced properties. In this work, we prepared lignin-containing copolymer macrostructures by 3D printing of poly(ethylene glycol) diacrylate (PEGDA) and biobased methacrylated Kraft lignin. Studied lignin loading is up to 10 w/v %. Liquid crystal display stereolithography was used to 3D print models of varying complexities and sizes. We demonstrate that methacrylated lignin can be thoroughly dissolved within the polyPEGDA matrix. This enables the adjustment of light shielding, mechanical performance, and antioxidant activity in the final high-resolution 3D-printed materials. Adding just 1 w/v % of the lignin-based component to the translucent (visible light) and brittle polyPEGDA reduces the transmittance of visible light to only 30% (at 550 nm). Additionally, it improves the elongation at break by a factor of 1.5 when compared with pure PEGDA-based resins. Moreover, the antioxidant properties of lignin further enhance the materials, resulting in approximately 40% antioxidant activity. The 3D-printed materials under study can then be considered as structures that block light and inhibit oxygen, making them suitable for applications in biotechnology.