Controlled One‐Pot Synthesis of Polystyrene‐<i>block</i>‐Polycaprolactone Copolymers by Simultaneous RAFT and ROP

<jats:p>A convenient one‐pot method for the controlled synthesis of polystyrene‐<jats:italic>block</jats:italic>‐polycaprolactone (PS‐<jats:italic>b</jats:italic>‐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 ε‐caprolactone. One‐pot poly­merizations using the electrochemically stable ROP catalyst diphenyl phosphate (DPP) yield well‐defined PS‐<jats:italic>b</jats:italic>‐PCL in a relatively short reaction time (≈4 h; <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/macp201300416-math-0001.png" xlink:title="urn:x-wiley:10221336:macp201300416:equation:macp201300416-math-0001" />= 9600−43 600 g mol<jats:sup>−1</jats:sup>; <jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/macp201300416-math-0002.png" xlink:title="urn:x-wiley:10221336:macp201300416:equation:macp201300416-math-0002" />/<jats:inline-graphic xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="graphic/macp201300416-math-0003.png" xlink:title="urn:x-wiley:10221336:macp201300416:equation:macp201300416-math-0003" /> = 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)<jats:sub>2</jats:sub> ROP catalyst reacts with <jats:bold>(1)</jats:bold> leading to multimodal distributions of polymer chains with variable composition. <jats:boxed-text content-type="graphic" position="anchor"><jats:graphic xmlns:xlink="http://www.w3.org/1999/xlink" mimetype="image/jpg" position="anchor" specific-use="enlarged-web-image" xlink:href="graphic/macp201300416-abs-0001-m.jpg"><jats:alt-text>image</jats:alt-text></jats:graphic></jats:boxed-text></jats:p>