Electrospun polyacrylonitrile nanofibers surface-functionalized with amidoxime groups and their applications

The innovative nanoengineering technique of electrospinning provides a straightforward and versatile approach to make various nanofibers with diameters typically ranging from tens to hundreds of nanometers. Electrospun polyacrylonitrile (ESPAN) nanofiber has been used in the field of filtration and textiles due to small diameters and the concomitant high specific surface area in addition to its thermal stability, high mechanical property, and chemical resistivity. ESPAN nanofiber is also a precursor to make carbon nanofibers. Recently, amidoxime surface-functionalized ESPAN (ASFPAN) nanofibers have attracted growing attentions because amidoxime functional groups (-C(NH₂)=N-OH) can coordinate with a variety of metal ions, and the coordinated metal ions can be further reduced to metal nanoparticles on nanofiber surface. In this chapter, the preparation, characterization and application of ASFPAN nanofibers are presented. The-CN groups on the surface of ESPAN nanofibers react with hydroxylamine (NH₂OH) molecules and lead to the formation of-C(NH₂)=N-OH groups for coordination of metal ions. The coordinated metal ions are subsequently converted into metal nanoparticles. The morphology and structure of ASFPAN nanofibers surface-attached with Ag nanoparticles as well as carbon nanofibers (derived from ASFPAN) surface-attached with Pd nanoparticles are investigated and their respective applications in antimicrobial filtration and hydrogen sensing are explored. The results suggest that ASFPAN nanofibers could be a precursor of choice to make nanofibrous mat, membrane, or felt with surface-attachment of metal nanoparticles for a wide range of applications where flexibility, space saving or production constraints is required.