Chemistry and Biochemistry
Bayer School of Natural and Environmental Sciences
Stephanie J. Wetzel
John F. Stolz
Atom Transfer Radical Polymerization, Catalysis, Hydrophilic Polymers, Mass Spectrometry
Due to the toxicity of heavy metals and their prevalence in the environment there exists a need to develop highly active transition metal catalysts ultimately reducing the amount needed for chemical transformations. Additionally, there is interest in the scientific community for creating new materials that can remove these pollutants from industrial wastewater prior to its release into the environment. The work presented here focuses on the reduction and removal of heavy metals from industrial hazardous waste by designing novel highly active catalysts and developing polymeric adsorbents.
Highly active catalyst complexes consisting of novel hybrid ligands, 2-(dimethylamino)ethyl-bis-[2-(pyridylmethyl)amine] (M1-T2), and bis[2-(dimethylamino)ethyl]-2-(pyridylmethyl)amine (M2-T1), were developed for atom transfer radical processes, i.e. atom transfer radical addition and atom transfer radical polymerization. The catalyst complexes were structurally similar to those containing tris(2-pyridylmethyl)amine (TPMA) or tris[2-(dimethylamino)ethyl]amine (Me6TREN) ligands. The Cu2+ complexes possessed distorted trigonal bipyramidal structures in solution and in the solid state. Electrochemical and kinetic evaluation indicated that the catalyst complexes containing the novel hybrid ligands should be more active in atom transfer radical processes than those containing the TPMA ligand. The novel highly active catalysts developed in this work were more efficient for atom transfer radical addition of monohalogenated alkyl halides to alkenes doubling percent yield of monoadduct in comparison to the TPMA analogue.
Homopolymers, poly(2-hydroxyethyl methacrylate) (PHEMA) and 2-(dimethylamino)ethyl methacrylate (PDMAEMA), and random copolymer, poly(HEMA-ran-DMAEMA) were synthesized via atom transfer radical polymerization. Ultimately, fragmentation pattern analysis using multi-stage mass spectrometry was performed to elucidate monomer sequence of the random copolymers. It was determined that the loss of ethylene glycol provides insight regarding the monomer sequence since it can only arise from adjacent HEMA monomers in the polymer backbone.
Two polymeric adsorbents, PHEMA and poly(acrylamide-co-acrylic acid), were implemented for the removal of Pb2+ from aqueous systems. Inductively coupled plasma mass spectrometry was utilized to quantify Pb2+ concentrations pre and post adsorption. Preliminary results indicate that both adsorbents PHEMA and poly(AAm-co-AAc), removed 99% and 21% of Pb2+, respectively. This data suggests their potential to be utilized for water remediation applications.
Novak, M. (2020). Atom Transfer Radical Processes: From Catalyst Design to Polymer Synthesis, Characterization, and Application (Doctoral dissertation, Duquesne University). Retrieved from https://dsc.duq.edu/etd/1943
Available for download on Saturday, December 18, 2021