Controlled Polymer Synthesis Toward Green Chemistry: Deep Insights into Atom Transfer Radical Polymerization in Biobased Substitutes for Polar Aprotic Solvents.

Abstract

Cyrene (dihydrolevoglucosenone) and its derivative Cygnet 0.0, recognized as eco-friendly alternatives to polar aprotic solvents, were utilized in atom transfer radical polymerization (ATRP) of a wide range of both hydrophobic and hydrophilic (meth)acrylates. The detailed kinetics study and electrochemical experiments of the catalytic complex in these solvents reveal the opportunities and limitations of their use in controlled radical polymerization. Both solvents produce precisely controlled polymers using supplemental activator and reducing agent (SARA) ATRP. They offer an efficient reaction medium for crafting well-defined branched architectures from naturally derived cores such as riboflavin, β-cyclodextrin, and troxerutin, thereby significantly expanding the application scope of these solvents. Notably, Cygnet 0.0 significantly reduces side reactions between the solvent and the catalyst compared to Cyrene, allowing the catalyst complex to be used at a reduced concentration down to 75 ppm. The effective mass yield values achieved in Cyrene and Cygnet 0.0 underscore a substantial advantage of these solvents over DMF in generating processes that adhere to the principles of green chemistry. Furthermore, the copper residue in the final polymers was several hundred times lower than the permissible daily exposure to orally administered copper in pharmaceuticals. As a result, the resulting polymeric materials hold immense potential for various applications, including the pharmaceutical industry.