Anionic polymerization of n-hexyl isocyanate with monofuctional initiators.: Synthesis of well-defined diblock copolymers with styrene and isoprene

Several monofunctional initiators, such as s-BuLi, 1,1-diphenyl-4-methylpentyl lithium (DPMPL), benzyl potassium (BzK), triphenylmethyl sodium (trityl sodium, TrNa) and benzyl sodium (BzNa) were tested and evaluated for the polymerization of n-hexyl isocyanate (HIC) in THF at -98 degrees C. The polymerizations were conducted either without or with additives, such as LiBPh4, NaBPh4, and crown ether 18C6. The products were characterized by size exclusion chromatography (SEC), membrane osmometry (MO), and H-1 NMR spectroscopy. The best results regarding polymerization yield, molecular weight distribution, and agreement between the stoichiometric and the experimentally observed molecular weight were obtained by the initiating system BzNa/NaBPh4 in a molar ratio 1/10. By using BzNa/NaBPh4 system, well-defined block copolymers of HIC with styrene or isoprene were synthesized for the first time. (c) 2005 Wiley Periodicals, Inc.