Controlled One-pot Synthesis of Polystyrene-b-Polycaprolactone Copolymers by Simultaneous RAFT and ROP

AUGUSTO G. O. DE FREITAS; SUELEN G. TRINDADE; PAULO I. R. MURARO; VANESSA SCHMIDT; ANGEL J. SATTI; MARCELO A. VILLAR; ANDRÉS E. CIOLINO; CRISTIANO GIACOMELLI

MACROMOLECULAR CHEMISTRY AND PHYSICS

WILEY-V C H VERLAG GMBH

Lugar: Weinheim; Año: 2013 vol. 214 p. 2336 - 2344

1022-1352

A convenient one-pot method for the controlled synthesis of polystyrene- block -polycaprolactone (PS- b -PCL) copolymers by simultaneous reversible addition¨Cfragmentation 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 e-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 (4 h, M n between 9,600 and 43, 600 g per mol ; M w / M n between 1.21 and 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.