A nearly quantitative synthetic approach towards monocyclic polystyrenes and the solvent, concentration and molecular weight effect on cyclic yield
A nearly quantitative synthetic approach towards monocyclic polystyrenes and the solvent, concentration and molecular weight effect on cyclic yield
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DOI：
10.1016/j.polymer.2016.08.086
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发表时间：
2016-09
期刊：
影响因子：
4.6
通讯作者：
Ling-feng Gao;Joongsuk Oh;T. Chang;Dongxue Chen;Xiaohong Li;Xiaoming Yang;Y. Tu;Xiu-lin Zhu
中科院分区：
文献类型：
--
作者：
Ling-feng Gao;Joongsuk Oh;T. Chang;Dongxue Chen;Xiaohong Li;Xiaoming Yang;Y. Tu;Xiu-lin Zhu
本文报道了溶剂、浓度和分子量对α-炔基-ω-叠氮基聚苯乙烯（I-PS-N3）链内偶联合成单环聚苯乙烯（c-PS）的影响。以完全末端官能化的1-PS-N_3为前体，在DMF中合成高纯度c-PS的最佳环化反应条件为7.9 μmol/L左右。通过SEC、LCCC、1H NMR和MALDI-TOF质谱对产物进行了表征。根据Jacobson和Stockmayer方程预测，c-PS的产率随n-PS-N3浓度的增加而降低。有趣的是，在所研究的三种不同分子量的PS样品中，中等分子量（PS 9 k）提供了最好的c-PS产率，而在所研究的三种溶剂（甲苯，DMF，环己烷）中，DMF提供了最好的产率。结果表明，溶液中的PS链构象受溶剂和分子量的影响，在链内环化反应中起着重要的作用。
We report herein the effects of solvent, concentration, and molecular weight of α-alkynyl-ω-azido polystyrenes (l-PS-N3) on the synthesis of monocyclic polystyrenes (c-PS) by intra-chain coupling ofl-PS-N3viaCu-catalyzed azide/alkyne cycloaddition method. By using fully end-functionalizedl-PS-N3as precursors, the optimum cyclization conditions to synthesize high purityc-PS (>99% by SEC) are revealed, at concentrations around 7.9 μmol/L in DMF. Thec-PS products are fully characterized by SEC, LCCC,1H NMR, and MALDI-TOF Mass spectrometry. The yield ofc-PS decreases with increment of concentration ofl-PS-N3as predicted by Jacobson and Stockmayer's equation. Interestingly, among the three studied PS samples with different molecular weight (∼4k, 9k, 14k Da), the medium one (PS9k) provides the bestc-PS yield, while in the three studied solvent (toluene, DMF, cyclohexane), DMF gives the best yied. The results reveal that the PS chain conformation in the solution, which is affected by the solvent and molecular weights, plays an important role in the intra-chain cyclization reaction.