Light-Driven Organocatalyzed Controlled Radical Polymerization from Sulfonyl Chloride Initiators Promoted by Bis(thiocarbonyl) Disulfides

Abstract

Organocatalyzed photo-controlled radical polymerizations (photo-CRPs) have gained increasing interest in tailoring polymers with spatiotemporal regulation. In this work, we have developed an organocatalyzed photo-CRP with various sulfonyl chlorides as initiators by using disulfides as chain transfer agents. In contrast to well-established metal-catalyzed CRPs from sulfonyl initiators, this method not only enables controlled synthesis of polymers without demanding a transition-metal catalyst at room temperature, but also facilitates "ON/OFF" temporal control using LED light as an external trigger. Proton nuclear magnetic resonance and matrix-assisted laser desorption/ionization time-of-flight mass spectroscopies have evidenced the chemical structure of polymers with both sulfonyl and trithiocarbonate terminals. Chain extensions with different macro-initiators and monomers have been successfully conducted to yield block copolymers, suggesting the good chain-end fidelity of polymers obtained in this reaction. We believe that this method represents an attractive metal-free approach to obtain tailored polymers with readily available sulfonyl chlorides as alternative initiators driven by light.

Photoiniferter-RAFT polymerization mediated by bis(trithiocarbonate) disulfides

“…44 Bis(thiocarbonyl) disulfides were also used as chain transfer agents in organo-catalysed photocontrolled radical polymerization with sulfonyl chlorides as initiators. 45 The potential of disulfides as agents capable of both initiating and reversibly deactivating polymer chain growth has been recognised as early as the late 1950s by Otsu and co-workers both in photo- and thermal-iniferter systems. 19 Using our understanding of both reversible termination and degenerative chain transfer, we aim to study this type of system in depth.…”