Depolymerized lignin (DPL), obtained as a product of catalytic transfer hydrogenolysis of organosolv lignin, was used in this study to generate lignin & methyl methacrylate (MMA) based photopolymers. Initially, the functional groups (-OH) of DPL were modified to append a methacrylate moiety and then bulk polymerized with methyl methacrylate (90% w/w) in the presence of UV-Vis-activated (365 to 405 nm) radical initiator, BAPO (bisacylphosphine oxide). Kinetic studies using real-time FTIR showed that the photo-polymerization rate of DPL-MMA resin (0.009 s-1) was twice as fast as the control (0.004 s-1). Thermogravimetric analysis showed that the DPL-MMA copolymer had a single prominent decomposition domain near 400 °C, which was superior to PMMA (poly-methyl methacrylate). Dynamic mechanical analysis showed that the Tg of DPL-MMA copolymer increased by 10 °C, whereas the viscous modulus (G”) decreased by 1 fold in magnitude when compared to PMMA. Therefore, crosslinking with bi-functional DPLs reduced the linear polymer’s flexibility, as well as increased the material stiffness. Finally, we also used lignin model compounds, namely 4-ethyl guaiacol and apocynol, to elucidate the changes in photopolymer properties brought upon by the variable nature of DPLs.

Depolymerized lignin & acrylate-based renewable photopolymers

255th National Meeting (2018)

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