Polyacrylonitrile nanofibers: Formation mechanism and applications as a photoluminescent material and carbon-nanofiber precursor

The facile synthesis of polyacrylonitrile (PAN) nanofibers is achieved using a microemulsion polymerization. The detailed formation mechanism of polymer nanofibers is examined using electron microscopy and UV-vis and Fourier transform infrared spectroscopies, and the optoelectronic properties are studied by confocal laser scanning microscopy. The effects of surfactant properties, such as concentration, chain length, and ionic character, as well as monomer structure and polymerization temperature, on the structure of the resulting polymer nanofibers are also investigated extensively. Importantly, PAN nanofibers exhibited novel photoluminescence (PL), which is observed for the first time. The PL of PAN nanofibers is significantly different from that of PAN nanoparticles. The PAN nanofibers are also used as a precursor for carbon nanofibers. The carbonization temperature has a dominant effect on the degree of crystallinity of the resulting carbon nanofibers. This study is the first demonstration of the fabrication of polymer and carbon nanofibers using a convenient polymerization technique.