Study of a new titanium dual initiator for the synthesis of poly(ε‐caprolactone)‐b‐polystyrene block copolymers by the combination of coordination and nitroxide mediated polymerizations

Abstract

ABSTRACT:Poly e-caprolactone-polystyrene blockcopolymers (PCL-b-PSt) were synthesized using a modified titanium catalyst as the dual initiator. Alcoholysis of Ti(OPr) 4 by 4-hydroxy 2,2,6,6 tetramethyl piperidinyl-1-oxyl (HO-TEMPO) gave a bifunctional initiator Ti(O-TEMPO) 4 . Poly e-caprolactone prepolymer end-capped with the nitroxide group was first prepared by ring opening polymerization of e-caprolactone with this initiator at high conversion. The nitroxide-end-capped structure and molar mass (M n ) of the polymers were demonstrated by typical UV absorption band. This analytical technique indicates a near-quantitative nitroxide functionality and a M n in good agreement with size exclusion chromatography (SEC) ones. This polyester prepolymer was used to further initiate the radical polymerization with styrene and reach the block copolymers (PCL-b-PSt). All the prepolymers and block copolymers were characterized by SEC and NMR spectroscopy. Additionally, the preparation of star polymers bearing two kinds of arms (PCL and PSt) was envisaged and a preliminary result was given.

Controlled ring-opening polymerisation of cyclic esters: polymer blocks in self-assembled nanostructures

“…147 Also, isolation of Ti-TEMPO complex by addition of 4 equivalents to TiO i Pr 4 for ROP of e-caprolactone followed by NMP of styrene in bulk; led to broad molecular weight distribution (TEMPO = 2,2,6,6-Tetramethylpiperidine-1-oxyl radical). 164 14 One pot NMP, ROP and click of styrene, e-caprolactone (Sn(Oct) 2 catalysed) and azide functional poly(ethylene glycol) (CuBr-PMDETA catalysed). 165 15 As part of miktoarm star polymer synthesis, simultaneous NMP of styrene and ROP of e-caprolactone catalysed by Sn(Oct) 2 were carried out in bulk at 120 1C.…”