Methacrylated\nBiosyrups of Depolymerized Lignin for\nRadiation-Curable Bioaromatic Resins and Functional Nanoscale Coatings

Radiation-curable resins display some intrinsic sustainable\nadvantages\nsince they are solvent-free and require less energy to cure but are\nstill largely derived from fossil resources. This lack of renewability\nis especially notable for the important class of aromatic precursors\nthat impart unique properties to the final materials. Herein, we report\na new class of photocurable resins derived from depolymerized lignin\noil, an emerging class of bio-oil containing low molecular weight\nbioaromatic compounds such as lignin monomers, dimers, and small oligomers.\nTo do so, we implemented a two-step green synthetic pathway involving\nethoxylation of phenolic hydroxyls with ethylene carbonate followed\nby trans-esterification of aliphatic hydroxyls with methyl methacrylate,\nthus circumventing the use of traditional (and often toxic) acrylation\nreagents. This innovative approach was first applied to monomeric\n(hydroxy)alkylphenol model compounds, and then directly to a pinewood-derived\nlignin oil . Highly functionalized methacrylated bioaromatic precursors\nwere obtained directly as viscous liquids (without adding reactive\ndiluents), thus mimicking the acrylic “syrups” commonly\nused in industry. These reactive biosyrups were then UV-cured into\nfunctional materials, such as free-standing films and (nanoscale)\ncoatings, and their superior thermomechanical properties were thoroughly\ninvestigated, revealing important insights in their tunable structure–property\nrelationships. In summary, we introduce a new class of radiation-curable\nbioresins leveraging synergies between the sustainable benefits of\nUV systems and the unique bioaromatic structure of lignin oil and\ndemonstrating significant potential for a wide range of applications\nin the coatings, microelectronics, nanotechnology, or biomedical industries.