Browsing by Subject "pyrolysis"

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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.
Open Access
The formation and characterization of cyclodextrin functionalized polystyrene nanofibers produced by electrospinning
(2009) Uyar, Tamer; Havelund, R.; Hacaloglu J.; Zhou X.; Besenbacher F.; Kingshott P.
Polystyrene (PS) nanofibers containing the inclusion complex forming beta-cyclodextrin (β-CD) were successfully produced by electrospinning aimed at developing functional fibrous nanowebs. By optimization of the electrospinning parameters, which included varying the relative concentration of PS and β-CD in the solutions, bead-free fibers were produced. Homogeneous solutions of β-CD and PS in dimethylformamide (DMF) were used with concentrations of PS varying from 10% to 25% (w/v, with respect to DMF), and β-CD concentrations of 1% to 50% (w/w, with respect to PS). The presence of β-CD facilitated the production of bead-free PS fibers even from lower polymer concentrations as a result of the higher conductivity of the PS/CD solutions. The morphology and the production of bead-free PS/CD fibers were highly dependent on the β-CD contents. Transmission electron microscope (TEM) and atomic force microscope (AFM) images showed that incorporation of β-CD yielded PS fibers with rougher surfaces. Thermogravimetric analysis (TGA) and direct insertion probe pyrolysis mass spectroscopy (DP-MS) results confirmed the presence of β-CD in the PS fibers. X-ray diffraction (XRD) spectra of the fibers indicated that the β-CD molecules are distributed within the PS matrix without any phase separated crystalline aggregates up to 40% (w/w) β-CD loading. Furthermore, chemical analyses by Fourier transform infrared (FTIR) spectroscopy studies confirm that β-CD molecules are located within the PS fiber matrix. Finally, preliminary investigations using x-ray photoelectron spectroscopy (XPS) and time-of-flight static secondary ion mass spectrometry (ToF-static-SIMS) show the presence of the cyclodextrin molecules in the outer molecular layers of the fiber surfaces. The XPS and ToF-SIMS findings indicate that cyclodextrin functionalized PS webs would have the potential to be used as molecular filters and/or nanofilters for the purposes of filtration/purification/separation owing to surface associated β-CD molecules which have inclusion complexation capability. © 2009 IOP Publishing Ltd.