Soda lignin as a sustainable photosensitive component for conventional and controlled radical photopolymerization
Min Wang, Xiongfei Luo, Qunying Wang, Veronika Strehmel, Zhijun Chen, Shujun Li, Bernd Strehmel
Abstract Valorization of waste for chemical processes addresses a challenging task for the society. Soda lignin (AL) available in the pulp industry operated in a photocatalytic cycle CuX2/L (X: Br, Cl; L: Me6TREN: Tris[2-(dimethylamino)ethyl]amine) and to initiate radical photopolymerization of methyl methacrylate (MMA) with α-bromophenylacetate (EBPA) by exposure at 420 nm. This resulted in poly(methyl methacrylate) (PMMA) exhibiting a dispersity <1.3 with CuX2/L loading of ≲52 ppm. Deactivator reduction increased dispersity. MMA, styrene, and benzyl methacrylate successfully served as monomers for chain extension and block copolymerization experiments. This worked with CuX2/L ≥ 6.5 ppm, although conventional radical polymerization additionally competed. Adding of sodium pyruvate enabled radical photopolymerization under air. Modification of lignin with an aryl sulfonate group resulted in a one-component photoinitiator. It successfully initiated radical photopolymerization of a monomer mixture of (hydroxyethyl)methacrylate (HEMA) and urethane dimethacrylate (UDMA). Scale-up experiments approved practicability of photo-ATRP.
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:Communications Chemistry
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