Abstract The use of weak bases as accelerators for reversible addition-fragmentation chain transfer radical polymerization (RAFT) of isoprene is demonstrated. Adding weak bases to RAFT polymerization, the conversion of isoprene could be greatly improved and reach about 50%. The effects of weak base on the polymerization were investigated. The living and controlled character of the RAFT polymerization of isoprene was confirmed by the linear increase in molecular weight with monomer conversion, the narrow molecular weight distribution and synthesis of polyisoprene-block-polystyrene (PIP-b-PS) block copolymer. The results of 1HNMR spectroscopy show that the structure of polyisoprene (PIP) with weak bases as accelerators was the same to the structure of PIP without any accelerator. The data presented here prove that weak bases are an efficient accelerator to inhibit Diels-Alder reaction of isoprene in the RAFT polymerization. GRAPHICAL ABSTRACT Weak bases were used as accelerators for reversible addition-fragmentation chain transfer radical polymerization (RAFT) of isoprene. Diels-Alder reaction of isoprene in RAFT polymerization was inhibited by adding a small amount of weak alkaline monomer (4-methyl-5-vinylthiazole and 4-vinylpyridine), and the conversion of isoprene was greatly increased. Some weak bases including pyridine, bipyridine, oxazole, pyrazole, benzothiazole and quinoline, were used to inhibit Diels-Alder reaction of isoprene. The living and controlled character of the RAFT polymerization of isoprene was confirmed by the linear increase in molecular weight with monomer conversion, the narrow molecular weight distribution and synthesis of polyisoprene-block-polystyrene (PIP-b-PS) block copolymer.

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弱碱，异戊二烯 RAFT 的有效促进剂

摘要 证明了使用弱碱作为异戊二烯可逆加成断裂链转移自由基聚合 (RAFT) 的促进剂。在RAFT聚合中加入弱碱，异戊二烯的转化率可大大提高，可达50%左右。研究了弱碱对聚合的影响。异戊二烯 RAFT 聚合的活性和可控特性通过分子量随单体转化的线性增加、窄分子量分布和聚异戊二烯-嵌段-聚苯乙烯 (PIP-b-PS) 嵌段共聚物的合成得到证实。1HNMR谱结果表明，以弱碱为促进剂的聚异戊二烯（PIP）的结构与不加任何促进剂的PIP结构相同。这里提供的数据证明弱碱是抑制 RAFT 聚合中异戊二烯的 Diels-Alder 反应的有效促进剂。图形摘要 弱碱被用作异戊二烯可逆加成断裂链转移自由基聚合 (RAFT) 的促进剂。通过加入少量弱碱性单体（4-甲基-5-乙烯基噻唑和4-乙烯基吡啶）抑制RAFT聚合中异戊二烯的Diels-Alder反应，大大提高了异戊二烯的转化率。一些弱碱包括吡啶、联吡啶、恶唑、吡唑、苯并噻唑和喹啉，用于抑制异戊二烯的Diels-Alder反应。异戊二烯 RAFT 聚合的活性和可控特性通过分子量随单体转化的线性增加得到证实，