Browsing by Author "Kingshott, P."
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Item Open Access Characterisation of internal morphologies in electrospun fibers by X-ray tomographic microscopy(Royal Society of Chemistry, 2011) Nygaard, J. V.; Uyar, Tamer; Chen, M.; Cloetens, P.; Kingshott, P.; Besenbacher, F.Electrospun fabrics for use in, for example, tissue engineering, wound dressings, textiles, filters and membranes have attracted a lot of attention due to their morphological nanoscale architectures which enhance their physical properties. A thorough detailed internal morphological study has been performed on electrospun polystyrene (PS) fibers produced from dimethylformamide (DMF) solutions. Investigations by transmission electron microscopy (TEM) and thorough studies for the first time by synchrotron based X-ray tomographic microscopy (XTM) revealed that the individual electrospun PS fibers and beads have a graded density and in some cases even an internal porous structure. © The Royal Society of Chemistry 2011.Item Open Access Cyclodextrin functionalized poly(methyl methacrylate) (PMMA) electrospun nanofibers for organic vapors waste treatment(Elsevier BV, 2010) Uyar, Tamer; Havelund, R.; Nur, Y.; Balan, A.; Hacaloglu, J.; Toppare, L.; Besenbacher, F.; Kingshott, P.Poly(methyl methacrylate) (PMMA) nanofibers containing the inclusion complex forming betacyclodextrin (_-CD) were successfully produced by means of electrospinning in order to develop functional nanofibrous webs for organic vapor waste treatment. Electrospinning of uniform PMMA nanofibers containing different loadings of _-CD (10%, 25% and 50% (w/w)) was achieved. The surface sensitive spectroscopic techniques; X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) showed that some of the _-CD molecules are present on the surface of the PMMA nanofibers, which is essential for the trapping of organic vapors by inclusion complexation. Direct pyrolysis mass spectrometry (DP-MS) studies showed that PMMA nanowebs containing _-CD can entrap organic vapors such as aniline, styrene and toluene from the surroundings due to inclusion complexation with _-CD that is present on the fiber surface. Our study showed that electrospun nanowebs functionalized with cyclodextrinsmayhave the potential to be used as molecular filters and/or nanofilters for the treatment of organic vapor waste and air filtration purposes.Item Open Access Functional electrospun polystyrene nanofibers incorporating α-, β-, and γ-cyclodextrins: Comparison of molecular filter performance(2010) Uyar, Tamer; Havelund, R.; Hacaloglu, J.; Besenbacher, F.; Kingshott, P.Electrospinning has been used to successfully create polystyrene (PS) nanofibers containing either of three different types of cyclodextrin (CD); α-CD, β-CD, and γ-CD. These three CDs are chosen because they have different sized cavities that potentially allow for selective inclusion complex (IC) formation with molecules of different size or differences in affinity of IC formation with one type of molecule. The CD containing electrospun PS nanofibers (PS/CD) were initially characterized by scanning electron microscopy (SEM) to determine the uniformity of the fibers and their fiber diameter distributions. X-ray photoelectron spectroscopy (XPS) was used to quantitatively determine the concentration of each CD on the different fiber surfaces. Static time-of-flight secondary ion mass spectrometry (static-ToF-SIMS) showed the presence of each type of CD on the PS nanofibers by the detection of both the CD sodium adduct molecular ions (M + Na+) and lower molecular weight oxygen containing fragment ions. The comparative efficiency of the PS/CD nanofibers/nanoweb for removing phenolphthalein, a model organic compound, from solution was determined by UV-vis spectrometry, and the kinetics of phenolphthalein capture was shown to follow the trend PS/α-CD > PS/β-CD > PS/γ-CD. Direct pyrolysis mass spectrometry (DP-MS) was also performed to ascertain the relative binding strengths of the phenolphthalein for the CD cavities, and the results showed the trend in the interaction strength was β-CD > γ-CD > α-CD. Our results demonstrate that nanofibers produced by electrospinning that incorporate cyclodextrins with different sized cavities can indeed filter organic molecules and can potentially be used for filtration, purification, and/or separation processes. © 2010 American Chemical Society.