Electrospinning is a facile nanofabrication technique that produces fibrous assemblies of ultra-fine fibers, 20–1000 nm in diameter, from a charged droplet of spinning solution. Optimization of the fiber diameter of a specific material system is dependent on the solution and process variables. The electrospinning parameters for poly (acrylic acid) (PAA), a synthetic polyelectrolyte, were systematically investigated and consistent nanofiber diameters with uniform morphology were achieved. The optimization matrix included several solvent systems including ethanol, aqueous NaCl and aqueous NaOH. Optimized spinning parameters were then applied to electrospinning fluorescent fibrous assembles of quantum dot-PAA ultra-fine fiber composites. Ultrafine composite fibers were prepared by electrospinning aqueous solutions of 6wt% PAA loaded with 0.05, 0.10, 0.15 and 0.20%v/v, carboxylic acid functionalized CdSe/ZnS nanoparticles (SNPs). The resulting composite fibers exhibited uniform fiber morphologies with increasing fiber diameters corresponding to increasing SNP loading. Fluorescence micrographs reveal luminescent fibers with evenly distributed fluorophores in the higher loaded samples. Moreover, laser excited fibers manifest SNP intermittency correlated with small clusters and single SNPs suggesting excellent dispersion in the PAA matrix.
Fabrication and Characterization of Electrospun Pristine and Fluorescent Composite Poly (acrylic acid) Ultra-Fine Fibers