Controlled One‐Pot Synthesis of Polystyrene‐block‐Polycaprolactone Copolymers by Simultaneous RAFT and ROP

A convenient one-pot method for the controlled synthesis of polystyrene-block-polycaprolactone (PS-b-PCL) copolymers by simultaneous reversible addition-fragmentation chain transfer (RAFT) and ring-opening polymerization (ROP) processes is reported. The strategy involves the use of 2-(benzylsulfanylthiocarbonylsulfanyl)ethanol (1) for the dual roles of chain transfer agent (CTA) in the RAFT polymerization of styrene and co-initiator in the ROP of epsilon-caprolactone. One-pot polymerizations using the electrochemically stable ROP catalyst diphenyl phosphate (DPP) yield well-defined PS-b-PCL in a relatively short reaction time (approximate to 4 h;(M) over barn= 9600-43600 gmol(-1);(M) over barw/(M) over barn = 1.21-1.57). Because the hydroxyl group is strategically located on the Z substituent of the CTA, segments of these diblock copolymers are connected through a trithiocarbonate group, thus offering an easy way for subsequent growth of a third segment between PS and PCL. In contrast, an oxidatively unstable Sn(Oct)(2) ROP catalyst reacts with (1) leading to multimodal distributions of polymer chains with variable composition.