Tailoring spatial distribution of Eu(TTA)3phen within electrospun polyacrylonitrile nanofibers for high fluorescence efficiency

Abstract

The influence of the distribution of the luminescent complex Eu(TTA)₃phen in electrospun polyacrylonitrile (PAN) nanofibers was explored in this work. Three different types of electrospinning (single fluid, traditional coaxial and a modified coaxial process) were employed to manipulate the distribution of Eu(TTA)₃phen in PAN nanofibers, producing systems with a uniform distribution of complex throughout the entire fibers or where it was localized only in the core or sheath of the fibers. TEM confirmed that the fibers produced had the expected nanoscale architectures and that the Eu(TTA)₃phen was distributed as desired in the PAN nanofibers through the selective application of different types of electrospinning processes. SEM and fluorescent tests proved that PAN nanofibers from the modified coaxial process had smooth surfaces, the narrowest diameters and the strongest fluorescent intensity. In the modified coaxial process, the sheath flow rate can be exploited to control the nanofibers' diameters; a sheath-to-core flow rate ratio of 0.1 and 0.2 gave PAN nanofibers with diameters of 380 ± 110 nm and 230 ± 70 nm, respectively. Modified coaxial electrospinning using a Eu(TTA)₃phen solution as a sheath fluid not only facilitates a smooth process providing nanofibers with reduced diameters, but also allows functionalization of the nanofibers through coating with functional components effectively, ensuring that the active Eu(TTA)₃phen is on the surface and leading to enhanced activity. The study reported herein, provides an example of the systematic design and preparation of advanced functional materials using different kinds of electrospinning processes.