Researcher(s)
- Jackson Sweet, Chemistry, The University of North Carolina at Chapel Hill
- Tulaja Shrestha, Chemistry, University of Delaware
Faculty Mentor(s)
- Laure Kayser, Department of Chemistry and Biochemistry and Department of Materials Science and Engineering, University of Delaware
Abstract
Polystyrene is a common source of plastic waste given that its recycling rate is only 0.9%. Modern polystyrene recycling methods, such as pyrolysis, are inefficient due to the low selectivity of the catalyst and formation of toxic byproducts including carbon dioxide and toluene. An alternative approach to polystyrene recycling, plastic upcycling, can counter these issues. Plastic upcycling is a modern alternative to previously used recycling methods in which waste material is converted into products with added value through chemical reactions. The conversion of styrene molecules into aryl sulfonamides has been documented in literature; however, these reactions have not yet been attempted on polystyrene. In this project, thianthrene was first attached to the polystyrene polymer. Thianthrene serves as an organocatalyst and enables the strong C-H bonds on the phenyl pendent of polystyrene in the para-position to be selectively replaced with more labile C-S bonds. Using traditional bench-scale synthesis, thianthrene was attached to the aryl group of polystyrene under nitrogen. High throughput experimentation was used to identify the optimal catalysts, solvents, and ligands necessary to convert thianthrenated polystyrene into hydroxymethyl polystyrene by adding Rongalite. It was discovered that Pd(dppf)Cl2 served as the best catalyst, DMSO was the best solvent, and monodentate ligands were optimal for synthesizing sulfonated polystyrenes. Once Rongalite is installed, the modified polystyrene can be amidated to produce polystyrene sulfonamides. Polystyrene sulfonamides have antimicrobial properties and applications to pharmaceutical science, adding value to the commodity polystyrene waste.