Cationic Dithiocarbamate for Efficient Blue Light-Controlled Photoiniferter Polymerization

N-phenyl-N-pyridin-1-ium dithiocarbamate was developed as a versatile iniferter for blue light-controlled radical polymerization. Tunable solubility in both water and various organic solvents was achieved through counterion exchange (Br– or PF6–). UV–visible absorption spectroscopy revealed strong blue light absorption. Kinetic studies for the photoiniferter polymerization of various monomers conducted using the dithiocarbamate in comparison with other iniferters revealed a combination of faster polymerization rates, shorter induction periods, and good control over molecular weights and molecular weight distributions. Electron paramagnetic resonance (EPR) studies demonstrated a faster photolysis rate for the dithiocarbamate compared to a trithiocarbonate iniferter. Photoiniferter polymerizations were conducted for N,N-dimethylacrylamide, N-acryloylmorpholine, methyl acrylate, poly(ethylene glycol) methyl ether acrylate (Mn = 480 g mol–1), and N,N-dimethyl lactamide acrylate in various solvents using the dithiocarbamate iniferter, yielding the corresponding homopolymers with controlled molecular weights (up to an Mn of 1316.8 kg mol–1) and narrow dispersities. High end-group fidelity was confirmed by 1H NMR spectroscopy and matrix-assisted laser desorption ionization time-of-flight (MALDI-TOF) mass spectrometry, enabling one-pot synthesis of well-defined diblock copolymers. Combining rapid kinetics, solvent versatility, and no requirement for acid additives, this system offers an accessible platform for precision polymer synthesis under mild, visible-light conditions.