钒化合物引发丙烯腈聚合──高分子场效应

研究了酸性介质中五价钒氧离子（VO）、强碱性阴离子交换树脂负载钒（V）（BAEV）、硫酸氧钒（VOSO4）、杨梅形聚羧酸氧钒（IV）（APCV）、杨酸形聚亚氨二乙酸氧钒（IV）（APIV）、杨梅形聚得偕亚氨二乙酸氧钒（IV）（APOV）、笼形聚羧酸氧钒（IV）（CPCV）和笼形聚肟偕亚氨二乙酸氧钒（IV）（CPOV）等与硫脲（TU）配住生成活性种并引发丙烯腈（AN）聚合反应。表观聚合速度（Rp）分别是：VO-TU:Rp=2.8X105e-14200/RTC2.2'(AN)c.20(HNO3)c0(V5+)c1.3(TU)BAEV-TU:Rp=1.9X104e-6860/RTc1.2(AN)c1.0'(HNO3)c0.44(PV)c1.0(TU)VOSO4-TU:Rp=0APCV-TU:Rp=2.3X104e-4100/Rtc1.5(AN)c1.5(HNO3)c0.5(PV)c2.0(TU)APIV-TU:RP=2.2X105e-6860/RTc1.0(AN)c2.0(H2SO4)c0.5(PV)c1.5(TU)APOV-TU:RP=1.9X108e-10800/RTc.10(AN)c1.0(HNO3)c0.6(PV)c1.5(TU)CPCV-TU:Rp=9.7X105e-10500/RTc1.0(AN)c1.5(HNO3)c0.5(PV)c0.76(TU)CPOV-TU:Rp=1.0X108e-10500/RTc1.0(AN)c3.0(HNO3)c1.0(PV)c1.5(TU)根据实验结果,认为：（一）钒化合物与硫脲在酸性介质中通过“逐步配位—质子转移”机理产生引发种;（二）钒络合物及其活化后所产生的阳离子自由基（i＝0,1,2,…,n）处于大分子引力场内进行链引发,在某些情况下,原地进行键增长反

Vanadium compounds for the polymerization of acrylonitrile-effect of mactromolecular field

The polymerization of acrylonitrile in acidic medium in the presence of the initiating systems composed of thiourea with pentavalent vanadium compounds such as vanadyl ion (VO) and strong basic anion exchange resin-Vanadyl (VO) complex (BAEV ),and with tetravalent vanadium copmounds, e. g.,vanadyl sulfate (VoSO4 ),the vanadyl (VO ) complexes of "arbutus" polycarboxylate (APCV )," arbutus" polytmidodiacetate (APIV ), " arbutus" poly (oxime - imidodiacetate ) (APOV ), " cage" polycarboxylate (CPCV ) and "cage" poly(oxime -hoidodiacetate) (CPOV ),respectively, were investigated. The overall rates of polpoerhation (Rp) were as follows: VO -TU: Rp = 2. 8 X 105e-14200/RT C2.2'(AN )c.20(HNO3 )c0 (V5+ )c1.3 (TU )BAEV -TU: Rp = 1. 9 X 104 e-6860/RT c1. 2(AN )c1.0'(HNO3)c0.44 (PV )c1.0 (TU )VOSO4 -TU: Rp =0APCV -TU: Rp = 2. 3 X 104 e-4100/Rt c1. 5(AN )c1.5 (HNO3)c0.5 (PV )c2.0 (TU )APIV -TU: RP =2. 2 X 105 e-6860/RT c1.0 (AN)c 2. 0 (H2SO4)c0.5 (PV)c1. 5 (TU )APOV -TU: RP = 1. 9 X 10 8e-10800/RT c.10 (AN)c1.0 (HNO3)c0. 6 (PV )c1.5(TU )CPCV -TU: Rp =9. 7 X 105 e-10500/RT c1. 0(AN)c1.5(HNO3)c0. 5 (PV )c0.76 (TU )CPOV -TU: Rp = 1.0 X 1 0 8e- 10500/RTc1.0 (AN )c3.0 (HNO3)c1. 0 (PV )c1. 5 (TU )On the basis of these experimental results, we considered that the polpoerization of acrylonitrile by thiourea with vanndium compounds in acidic medium, (1) the initiating speices are generated by the reaction of thiourea with vanadium compounds via the "stepwise coordination-proton transfer " mechanism" ; (2) the vanadium complexes and the derived Cation radicals, H2N= (H2N-) C-S-ANi. (i=0, 1, 2, ..., n ), are attracted by the macromolecu1ar field, the chain initiation and propagation thus carry out in situ ; (3)the central ion VO of the polymer complex is oxidford to be VO accelerated by the synergy effect of the adjacent polymer ligands ; (4) the steric hindrance of the macromolecular chains and their pendant groups governs the formation pathways of the monomeric radicals and the primary radicals it also affects the process of the chain termination in some caies: (5) the collision frequency factor and the overall activation energy of polymerization are always controlled by the effect of macromolecular field, the orders of both parmeters all are found to be APCV