LiCl-Promoted Chain Growth Kumada Catalyst-Transfer Polycondensation of the 鈥淩eversed鈥?Thiophene Monomer

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• 作者：Shupeng Wu ; Li Huang ; Hongkun Tian ; Yanhou Geng ; Fosong Wang
• 刊名：Macromolecules
• 出版年：2011
• 出版时间：October 11, 2011
• 年：2011
• 卷：44
• 期：19
• 页码：7558-7567
• 全文大小：1106K
• 年卷期：v.44,no.19(October 11, 2011)
• ISSN：1520-5835

文摘

The effect of LiCl on the chain growth Kumada catalyst-transfer polycondensation (KCTP) of the 鈥渞eversed鈥?thiophene monomer, 5-bromo-2-chloromagnesio-3-hexylthiophene (3a) (that has bulky substituent adjacent to the chloromagnesium group), was investigated. LiCl promotes the polymerization of 3a, and the polymerization also exhibits living characteristics similar to those of the 鈥渘ormal鈥?monomer, 2-bromo-5-chloromagnesio-3-hexylthiophene (3b). However, initiation is much slower than chain propagation due to the steric hindrance between hexyl groups in the transmetalation (TM) step that leads to the formation of the initiator via head-to-head (HH) coupling. Consequently, regioregular poly(3-hexylthiophene) (P3HT) with large polydispersity (PDI) and higher number-average molecular weight (M_n) than the theoretical value was obtained. Because of the slow initiation with 3a, the polymerization of 3a occurs primarily after the consumption of 3b in the copolymerization of 3a and 3b, and P3HT with high regioregularity was still obtained.