快速制备水溶性RAFT聚合链转移剂的方法研究

Study of Rapid Preparation of Water-Soluble RAFT Polymeric Chain Transfer Agents

可逆加成-断裂链转移自由基聚合(RAFT)是活性自由基聚合的一种,现有文献普遍存在RAFT链转移剂含有长链的憎水基团,通常在水溶液中溶解性很差的问题,这大大限制水溶液中RAFT聚合反应的进行,如何提高RAFT链转移剂在水中溶解度一直是广大科研工作者们研究的热点和难点。本文报道了一种创新性制备水溶性RAFT聚合链转移剂的方法:首先在碱性条件下将二硫化碳和乙硫醇反应,一段时间后加入碘单质反应制备六硫代碳酸酯化合物,然后再与4,4-双偶氮-双(4-氰基戊酸)制备得到4-氰基-4-[乙硫基(硫代羰基)硫代]戊酸,在此基础上再与聚乙二醇单甲醚通过酯化反应得到水溶性目标化合物2-[(2-甲氧基乙氧基)乙基]-4-氰基-4-[乙硫基(硫代羰基)硫代]戊酸酯。通过核磁共振氢谱对化合物纯度进行表征发现其纯度均已达到98%以上,水中溶解度大于100 mg/g。

Reversible addition-breakage chain transfer radical polymerization(RAFT)is a kind of reactive radical polymerization,and the existing literature generally has the problem that RAFT chain transfer agents contain long chains of water-repellent groups and are usually poorly soluble in aqueous solutions,which greatly limits the RAFT polymerization reaction in aqueous solutions.This paper reports an innovative method for the preparation of water-soluble RAFT polymerization chain transfer agents.Firstly,carbon disulfide and ethanethiol are reacted under alkaline conditions,and after a period of time,iodine monomers are added to prepare hexathiocarbonate compounds,and then 4-cyano-4-[ethylthio(thiocarbonyl)thio]pentanoic acid is prepared with 4,4-bis(azo)-bis(4-cyanopentanoic acid),and on this basis,4-cyano-4-[ethylthio(thiocarbonyl)thio]pentanoic acid is prepared with The water-soluble target compound 2-[(2-methoxyethoxy)ethyl]-4-cyano-4-[ethylthio(thio-carbonyl)thio]pentanoic acid was obtained by esterification with poly(ethylene glycol)monomethyl ether.The purity of the compounds was characterized by NMR hydrogen spectroscopy and found to be above 98%with a solubility of>100 mg/g in water.