Water-soluble/dispersible carbazole-containing random and block copolymers by nitroxide-mediated radical polymerisation

A series of carbazole-containing water-dispersible poly(acrylic acid)-b-(9-(4-vinylbenzyl)-9H-carbazole) block copolymers (poly(AA)-b-poly(VBK)) and water-soluble poly(methacrylic acid-ran-(9-(4-vinylbenzyl)-9H-carbazole)) (poly(MAA-ran-VBK)) random copolymers were synthesised in a controlled manner (i.e. low polydispersities $(\overline {M_{{\rm w}} } /\overline {M_{n} } < 1.3)$ by nitroxide-mediated polymerisation (NMP) using an SG1-based alkoxyamine initiator, BlocBuilder. Poly(AA)-b-poly(VBK) block copolymers were most easily accessed by using poly(AA) in its protected form as the macroinitiator for the 9-(4-vinylbenzyl)-9H-carbazole (VBK) block. Controlled polymerisation of MAA was accomplished using an excess of 10mol.% SG1 relative to BlocBuilder with VBK as controlling co-monomer (initial molar feed content fVBK,0=0.030.20) in dimethylformamide at 80 degrees C. Poly(MAA-ran-VBK) copolymers with a final VBK molar composition of FVBK<0.30 resulted in water-soluble copolymers. In addition, as macroinitiators, poly(MAA-ran-VBK)s were sufficiently pseudo-living to reinitiate a second batch of monomer (90mol.% methyl methacrylate with styrene) in organic solvent and by ab initio, surfactant-free emulsion polymerisation. In both cases, low polydispersity, amphiphilic block copolymers resulted $(\overline {M_{{\rm w}} } /\overline {M_{{\rm n}} } < 1.3)$. (c) 2012 Canadian Society for Chemical Engineering