Synthesis and multidimensional NMR characterization of PDMS-b-PS prepared by combined anionic ring-opening and nitroxide-mediated radical polymerization

The synthesis of PDMS-b-PS copolymers by anionic and nitroxide-mediated radical polymerization (NMRP) is discussed. Hydride end-capped PDMS is hydrosilylated with an allylic alkoxyamine to form a TEMPO functional macroinitiator. The macroinitiator is reacted with styrene to form diblock copolymer. NMRP of styrene initiated by the PDMS macroinitiator (M-w/M-n = 1.22) gave diblocks with M-w/M-n between 1.28 and 1.35. Microstructure characterization by one (1D) and two (2D) dimensional solution NMR verified the composition of the copolymer end groups and block junction. LC-NMR analysis shows that nearly homopolymer free diblocks were obtained by this method. Solid-state NAIR analysis verified a phase-separated morphology.