Molecular filters based on cyclodextrin functionalized electrospun fibers

Beta-cyclodextrin (β-CD) was successfully incorporated into polystyrene (PS) fibers by electrospinning technique. The subsequent fibrous membranes show potential for efficient removal of organic compound (e.g.: phenolphthalein) from solution by the formation of inclusion complexes with the β-CD molecules. Since the filtration efficiency of the fiber membranes is highly dependent on the presence and distribution of β-CD at the surface of the individual fibers, highly sensitive and specific surface spectroscopic analyses were carried out. X-ray photoelectron spectroscopy (XPS) was used to quantify the amount of β-CD on the surface of PS fibers. Time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed the presence of both β-CD molecular and fragment ions on the fiber surfaces, and high resolution chemical imaging demonstrated even distribution of β-CD on the surface of the individual fibers. Phenolphthalein (PhP) was used as a model compound in the filtration studies, and a strong dependence was observed between β-CD content of the PS/CD fibers and efficiency of trapping PhP. These results demonstrate the potential of using PS/CD fibrous membranes to filter organic molecules in purification/separation processes.