Acceleration of the single electron transfer-degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of vinyl chloride in water at 25 degrees C

摘要

The accelerated single electron transfer-degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of vinyl chloride (VC) in H2O/tetrahydrofuran (THF) at 25 degreesC is reported. This process is catalyzed by sodium dithionite (Na2S2O4)-sodium bicarbonate (NaHCO3). Electron transfer cocatalysts (ETC) 1,1'-dialkyl-4,4'-bipyridinum dihalides or alkyl viologens were also employed in this polymerization. The resulting poly(vinyl chloride) (PVC) has a number-average molecular weight (M-n) = 2,000-12,000, no detectable amounts of structural defects, and both active chloroiodomethyl and inactive chloromethyl chain ends. The molecular weight distribution of PVC obtained is M-w/M-n = 1.5. The surface active agents afford the final polymers as a powder and provide an acceleration of the rate of polymerization. The role of ETC is to accelerate the single electron transfer (SET) step, whereas THF enhances the degenerative chain transfer (DT) step. (C) 2004 Wiley Periodicals, Inc.