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 p. 2336 - 2344

1022-1352

A convenient one-pot method for controlled synthesis of polystyrene-b-polycaprolactone (PS-b-PCL) copolymers by simultaneous RAFT and ROP processes is reported. The strategy relies on the use of 2-(benzylsulfanylthiocarbonylsulfanyl)ethanol (1) for the dual role of chain transfer agent (CTA) in the RAFT polymerization of styrene, and of co-initiator in the ROP of ε-caprolactone. One-pot polymerizations using the electrochemically stable ROP catalyst diphenyl phosphate (DPP) yield well-defined PS-b-PCL in rather short reaction time (~ 4 h; Mn = 9600 − 43600 g/mol; Mw/Mn = 1.21 − 1.57). As the hydroxyl group is strategically located on the Z substituent of the CTA, segments of these diblock copolymers are connected through a trithiocaronate group, offering an easy way for subsequent growth of a third segment between PS and PCL. In contrast, oxidativelly unstable Sn(Oct)2 ROP catalyst interfered in RAFT process leading to multimodal distributions of polymer chains with variable compositions.