超顺磁性纳米催化剂在有机合成中的应用

超顺磁性纳米颗粒及其复合材料作为有机反应的催化剂,不仅能通过外加磁场实现催化剂的分离回收,且在反应介质中催化活性位点利用率高,可起到均相催化的效果。本文在系统总结近年来磁性纳米催化剂制备的基础上,阐述了磁性纳米催化剂的制备方法、结构类型和特点。同时,对催化剂在有机合成中的应用和催化效果进行了综述,对磁性纳米催化剂在反应中失活的原因做了详尽分析,展望了超顺磁性纳米颗粒的主要发展方向和今后仍需解决的问题。     

The Synthesis of Magnetic Core‐Shell Nanoparticles by Surface‐Initiated Ring‐Opening Polymerization of ε‐Caprolactone

Summary: The synthesis of core‐shell particles with a poly(ε‐caprolactone) (PCL) shell and magnetite (Fe₃O₄) contents of between 10 wt.‐% and 41 wt.‐% proceeds by surface‐initiated ring‐opening polymerization of ε‐caprolactone to give surface‐immobilized oligomers with between 1 400 g · mol⁻¹ and 11 500 g · mol⁻¹. The particles are dispersable in good solvents for the PCL shell. Magnetization experiments on the resulting superparamagnetic ferrofluids give a core‐size distribution with an average diameter, d_v, of about 9.7 nm.

TEM image of Fe₃O₄/PCL core‐shell particles cast from CHCl₃ dispersion.