Access to cyclic polystyrenes via a combination of reversible addition fragmentation chain transfer (RAFT) polymerization and click chemistry
Access to cyclic polystyrenes via a combination of reversible addition fragmentation chain transfer (RAFT) polymerization and click chemistry
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DOI：
10.1016/j.polymer.2008.03.017
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发表时间：
2008-04-29
期刊：
影响因子：
4.6
通讯作者：
Wuller, Axel H. E.
中科院分区：
文献类型：
--
作者：
Goldmann, Anja S.;Quemener, Damien;Wuller, Axel H. E.
将可逆加成断裂链转移(RAFT)聚合技术与铜催化的惠氏1，3-偶极环加成(CLICK化学)相结合，是合成聚苯乙烯(PS)大环的一种简单而有效的方法。这一新的策略需要合成线性PS主链，然后进行端基修饰，以促进形成环状聚合物的点击化学。用叠氮基修饰的4-氰基戊酸二硫代苯甲酸酯作为链转移剂，在RAFT引发的苯乙烯聚合中生成了聚苯乙烯，其M-n从2000~6000gmol(-1)，PDI<；1.2。为了通过点击偶联促进聚苯乙烯链的环化，硫代羰基硫代端基被移除，并伴随着由含炔官能团取代。这是通过过量的偶氮二(4-氰基戊酸)(ACVA)在硫代羰基硫代PS存在下用炔端基修饰的自由基分解来实现的。详细讨论了几种聚苯乙烯的成功的端基修饰，以及M-n=4300gmol(-1)的聚苯乙烯的环化反应结果。这种改进的方法避免了大环中硫代羰基功能的存在，从而大大提高了这些聚合物的化学稳定性。(C)2008爱思唯尔有限公司。保留所有权利。
The coupling of the reversible addition fragmentation chain transfer (RAFT) polymerization technique with the copper-catalyzed Huisgen 1,3-dipolar cycloaddition ("click chemistry") as a simple and effective way to generate polystyrene (PS) macrocycles is presented. The novel strategy entails the synthesis of linear PS backbones followed by endgroup modification to facilitate click chemistry for the formation of ring shaped polymers. An azido group modified 4-cyanopentanoic acid dithiobenzoate is employed as the chain transfer agent in the RAFT mediated polymerization of styrene to form PS with M-n from 2000 g mol(-1) to 6000 g mol(-1) and PDI < 1.2. To facilitate the cyclization of the polystyrene chains by click coupling, the thiocarbonylthio endgroup is removed and concomitantly replaced by an alkyne bearing function. This is carried out via the radical decomposition of excess azobis(4-cyano valeric acid) (ACVA) modified with an alkyne endgroup in the presence of the thiocarbonylthio-capped PS. The successful click endgroup modifications of several polystyrenes along with the results from the cyclization of a PS with M-n = 4300 g mol(-1) are discussed in detail. This improved method avoids the presence of thiocarbonylthio functions in the macrocycle, thus considerably increasing the chemical stability of these polymers. (C) 2008 Elsevier Ltd. All rights reserved.