Researcher(s)
- Caitlyn Edgar, Chemical Engineering, University of Delaware
Faculty Mentor(s)
- Christopher Kloxin, Chemical and Biomolecular Engineering, Materials Science and Engineering, University of Delaware
Abstract
Atom transfer radical polymerization (ATRP) is a form of radical polymerization which allows for precise control over a polymer’s properties. ATRP produces polymers with narrow molecular weight ranges and retains end group functionality, allowing for easy post-polymerization modification. ATRP in aqueous media is advantageous due to a lack of harsh chemicals required, cost effectiveness, and biological compatibility. ATRP of various polymers, including oligo(ethylene oxide) monomethyl ether methacrylate (OEOMA) and di(ethylene oxide) methyl ether methacrylate (DEGMA), is possible in aqueous media through the use of a copper-ligand complex catalyst and excess bromide ions in solution. However, if there is oxygen present in the reaction, it will continuously oxidize the catalyst and the polymerization will not proceed. In order to prevent this, sodium pyruvate is employed as a cocatalyst to remove oxygen from the reaction vessel.
In this study, tert-butyl bromoisobutyrate (tBiBB) was used as a small molecule initiator to provide insight on the impact of sodium pyruvate on ATRP reaction kinetics. For the OEOMA system, increasing the concentration of sodium pyruvate was found to decrease the incubation period, in which the reaction does not occur due to oxygen present in the system. Additionally, the average time required to reach near-full conversion from monomer to polymer decreased with increasing sodium pyruvate concentration. The polymerization kinetics of DEGMA did not appear to respond to increases in sodium pyruvate due to other concerns with the polymerization, including the polymer precipitating out of solution at a low conversion. These observations will inform others in choosing the optimal sodium pyruvate concentration for an efficient and effective polymerization. Future work includes observing how other components of the reaction may affect the kinetics, as well as applying varying levels of sodium pyruvate to a peptide initiator system.