Phase transfer catalyzed single electron transfer-degenerative chain transfer mediated living radical polymerization (PTC-SET-DTLRP) of vinyl chloride catalyzed by sodium dithionite and initiated with iodoform in water at 43 degrees C

摘要

To accelerate the living radical polymerization (LRP) of vinyl chloride (VC) in water the phase transfer catalyzed single electron transfer-degenerative chain transfer mediated living radical polymerization (SET-DTLRP) of VC mediated by Sodium dithionite (Na2S2O4) was investigated. The fastest polymerization reaction that-still produces thermally stable poly(vinyl chloride) (PVC) takes place at 43 degreesC with the ratio [PTC](0)/[Na2S2O4](0) = 0.0075/1. Cetyltrimethylammonium bromide (nC(16)H(33)(CH3)(3)N+Br-. CetMe(3)NBr) was the phase-transfer catalyst (PTC) of choice. Under these conditions the first, fast stage of SET-DTLRP of VC was accomplished within 7-8 h when the initial ratio monomer/initiator [VC](0)/[CHI3](0) was 800. The number-average molecular weight (M-n) of the resulting PVC was in good agreement with the theoretical molecular weight Of, When the [VC](0)/[CHI3](0) ratio was 4800, the fast step of the reaction was accomplished within 17 h, to produce 72% monomer conversion. A deviation of the M-n from the M-th was observed in this case. Possible mechanistic explanations for this deviation as: well as for the phase transfer catalyzed SET-DTLRP of VC were suggested. (C) 2005 Wiley Periodicals, Inc.