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[求助]
RAFT试剂对强酸的稳定性问题
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| 有做RAFT试剂的大神没，RAFT试剂（二硫酯）对有机强酸如三氟乙酸的稳定如何，能否在RAFT聚合的过程中加入强酸同时实现可控/"活性"聚合。 |
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shakete
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超级小笨瓜: 金币+4, ★★★很有帮助 2013-06-25 15:50:41
超级小笨瓜: 金币+4, ★★★很有帮助 2013-06-25 15:50:41
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Trithiocarbonates are known to be less subjected to hydrolysis than dithiobenzoate.(47, 48) However, a UV study performed at pH = 8.0 revealed that after only 30 min at 80 °C the absorbance of the PMAA macroRAFT agent at λ = 310 nm (corresponding to the maximum absorbance of the thiocarbonylthio function) decreased by 36% meaning that one-third of the chains had lost their RAFT chain end. After 5 h, only 14% of the chains still carried an active chain end. These results clearly explain the high amount of unreacted PMAA-CTPPA observed at this pH and the consequent poor control of the polymerization. By comparison, the hydrolytic stability of PMAA-CTPPA was significantly better at pH = 3.4 since a decay of only 4% was observed after 30 min at 80 °C and the proportion of living chains was still of 75% after 5 h (see Figure S2 in Supporting Information). In the emulsion polymerization performed at pH = 3.4, PMAA-CTPPA chains do not spend more than 45 min in the aqueous phase (Figure 1) and chain end hydrolysis can thus be neglected. 不知道怎么发图片，就把原句截下来了 http://pubs.acs.org/doi/full/10.1021/ma300875y这是文献的出处 atch Emulsion Polymerization Mediated by Poly(methacrylic acid) MacroRAFT Agents: One-Pot Synthesis of Self-Stabilized Particles |
5楼2013-06-25 09:48:19
shakete
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