The livingness of poly(methyl acrylate) under visible light photoiniferter-RAFT polymerization mediated by trithiocarbonates†

This study investigates the formation and evolution of dead chains during and after the photoiniferter-RAFT polymerization of poly(methyl acrylate). Thermal gradient high-performance liquid chromatography (TG-HPLC) was employed to quantify living and dead chains within the system. Through HPLC fractionation, dead chains were directly separated and further analyzed using ¹H NMR spectroscopy and gel permeation chromatography. The results demonstrated a linear increase in dead chain formation over time, likely attributed to the continuous removal of thiocarbonylthio (TCT) end groups from living chains. The relationship between light intensity and dead chain formation was also investigated; however, the dead fraction exhibited a linear increase regardless of light intensity. These findings underscore the critical importance of managing these dynamics to preserve the “living” nature of photoiniferter-RAFT systems.