2024 AIChE Annual Meeting
Photodegradation Kinetics of Trithiocarbonates
Aqueous reversible addition fragmentation chain transfer (RAFT) polymerization is a technique used to synthesize polymers with precise control over molecular weight and structure while offering a biocompatible and environmentally friendly alternative to traditional organic solvents. Light-mediated aqueous RAFT polymerizations in which the polymerization is initiated using UV or visible light enables spatiotemporal control over the polymerization process and offers benefits as light is safe, abundant, and inexpensive. However, use of water and UV light can lead to the hydrolysis and photodegradation of chain transfer agents, respectively. Therefore, consideration into polymerization conditions must be taken. This study investigates the degradation of a trithiocarbonate-containing RAFT agent in water when exposed to UV light at its peak absorbance of 310 nm, as a function of concentration, pH, and time. The photodegradation kinetics were monitored using UV-Vis spectroscopy to gain insights into the effects of UV exposure on these compounds. For the concentrations studied, first order reaction kinetics were observed, and rate constants and half-lives were determined. These findings enhance our understanding when using trithiocarbonate RAFT agents in photopolymerizations.