Synthesis and reversible photocleavage of novel polyurethanes containing coumarin dimer components

Yun Chen, Kong Hong Chen

研究成果: Article同行評審

72 引文 斯高帕斯(Scopus)

摘要

Six polyurethanes containing coumarin dimer components in the main chain have been prepared by polyaddition of diisocyanates with anti head-to-head 7-hydroxycoumarin dimer or anti head-to-tail 7-hydroxy-4-methylcoumarin dimer. 7-Acetoxycoumarin and 7-acetoxy4-methylcoumarin were first prepared and then photodimerized under 350 nm UV light to give anti head-to-head 7-acetoxycoumarin dimer and anti head-to-tail 7-acetoxy-4-methylcoumarin dimer, respectively. After hydrolyzing under acidic conditions to 7-hydroxycoumarin dimer and anti head-to-head 7-hydroxycoumarin dimer, they were polymerized with aliphatic and aromatic diisocyanates in N,N-dimethylacetamide to give the polyurethanes. Addition of dibutyltin dilaurate (T-12) as catalyst increases the polymer yield with the viscosity remaining almost unchanged. It was also found that lithium chloride enhances both the yield and viscosity of the polyurethanes by increasing their solubility possibly through complexation. The polyurethanes are symmetrically photocleaved at cyclobutane rings under 254 nm UV light to dicoumarins. Reversible photodimerization of the photocleavad compounds have also been investigated under 300 and 350 nm UV light. The polyurethanes from aromatic diisocyanates or with 4-methyl substituent exhibit greater reactivity in the photocleavage reaction.

原文English
頁(從 - 到)613-624
頁數12
期刊Journal of Polymer Science, Part A: Polymer Chemistry
35
發行號4
DOIs
出版狀態Published - 1997 1月 1

All Science Journal Classification (ASJC) codes

  • 聚合物和塑料
  • 有機化學
  • 材料化學

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