Water-Soluble Branched Polyacrylamides Prepared by UV-Initiated Polymerization Using a Novel Kind of Water-Soluble Macromolecular Photoinitiator

Branched polyacrylamides (PAMs) have shown tremendous potential in wastewater treatment, papermaking, and oil drilling due to their unique molecular structure, remarkable shear stability, and effective flocculability. Efficient approaches for their industrial-scale production have attracted increasing attention. Herein, we report a facile, scalable, highly efficient, and cost-effective strategy for the production of branched PAMs through UV polymerization of acrylamide (AM) initiated with a novel water-soluble macro-photoinitiator. Through precipitation copolymerization of AM and 2-hydroxy-1-[4-(2-acryloyloxyethoxy)pheny1]-2-methyl-l-propanone (M2959), poly(AM-co-M2959)s bearing pho- toinitiator moieties on the backbone were successfully synthesized, which showed excellent water solubility and high photoinitiation efficiency. Most importantly, both the branching degree and main-chain length of the branched PAMs were controllable, given that the molar mass and photoinitiating group content of poly(AM-co-M2959)s could be effectively controlled by adjusting the monomer feed ratio of AM/M2959. The rheological properties of the resultant branched PAMs were characterized in detail, and excellent water solubility and shear resistance were observed, confirming the well-defined branched structure of the as-prepared PAMs. Due to their facile synthesis, simplicity of operation, and high photoinitiation efficiency, these novel macro-photoinitiators have great potential as a versatile platform for the preparation of various branched polymers containing different functional groups (not limited to branched PAMs).