4-Halogeno-3,5-dimethyl-1H-pyrazole-1-carbodithioates: versatile reversible addition fragmentation chain transfer agents with broad applicability
4-Halogeno-3,5-dimethyl-1H-pyrazole-1-carbodithioates: versatile reversible addition fragmentation chain transfer agents with broad applicability
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DOI：
10.1002/pi.5423
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发表时间：
2017-11
影响因子：
3.2
通讯作者：
J. Gardiner;I. Martinez-Botella;Thomas M. Kohl;J. Krstina;G. Moad;J. Tyrell;M. Coote;J. Tsanaktsidis
中科院分区：
文献类型：
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作者：
J. Gardiner;I. Martinez-Botella;Thomas M. Kohl;J. Krstina;G. Moad;J. Tyrell;M. Coote;J. Tsanaktsidis
基于吡唑的二硫代氨基甲酸酯是通用的可逆加成断裂链转移（RAFT）试剂，其提供对更多和更少活化单体（MAM和LAM）的自由基聚合的摩尔质量和分散度（density）控制。在本文中，我们报告的理论和实验结果表明，它们的RAFT剂的活性可以显着提高通过引入吸电子取代基的吡唑环。这种增强在甲基丙烯酸甲酯聚合中是最明显的，其中通过RAFT试剂浓度更准确地预测产物摩尔质量，并且观察到相对于在类似条件下用母体RAFT试剂所观察到的那些，显著更低的α值。因此，使用4-氯-3，5-二甲基-1H-吡唑-1-硫代甲酸酯提供了在高单体转化率下具有预期摩尔质量和低至1.3的Mw的聚（甲基丙烯酸甲酯）。对于单取代的MAMs、苯乙烯、丙烯酸甲酯和N，N-二甲基丙烯酰胺保持良好的控制。对于与LAM乙酸乙烯酯的均聚和共聚，也实现了低分散性和较少的摩尔质量控制，尽管具有一些延迟。© 2017作者。Polymer International，由John Wiley & Sons Ltd代表化学工业协会出版。
Pyrazole-based dithiocarbamates are versatile reversible addition fragmentation chain transfer (RAFT) agents that provide molar mass and dispersity (Đ) control over the radical polymerization of both more and less activated monomers (MAMs and LAMs). In this paper we report on theoretical and experimental findings demonstrating that their activity as RAFT agents can be significantly enhanced by introducing electron-withdrawing substituents to the pyrazole ring. This enhancement is most noticeable in methyl methacrylate polymerization where product molar masses are more accurately predicted by the RAFT agent concentration, and significantly lower Đ values, with respect to those seen with the parent RAFT agent under similar conditions, are observed. Thus, use of 4-chloro-3,5-dimethyl-1H-pyrazole-1-carbodithioate provides a poly(methyl methacrylate) with the anticipated molar mass and Đ as low as 1.3 at high monomer conversion. Good control is retained for monosubstituted MAMs, styrene, methyl acrylate and N,N-dimethylacrylamide. Low dispersities and less molar mass control are also achieved for homo- and copolymerizations with the LAM vinyl acetate, albeit with some retardation. © 2017 The Authors. Polymer International published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.