Browsing by Author "Satilmis, B."

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    Fabrication of thermally crosslinked hydrolyzed polymers of intrinsic microporosity (hpım)/polybenzoxazine electrospun nanofibrous membranes
    (WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim, 2018) Satilmis, B.; Uyar, Tamer
    In this study, thermally crosslinked hydrolyzed polymers of intrinsic microporosity (HPIM)/polybenzoxazine electrospun nanofibrous membranes (NFMs) are successfully produced. The nanofibers having 800 ± 260 to 670 ± 150 nm average fiber diameters from HPIM and blends of HPIM/ benzoxazine (BA‐a) ranging from HPIM:(BA‐a) weight ratio of 9:1 to 2:1 w/w are produced by electrospinning. Self‐standing HPIM/(BA‐a) NFMs are thermally step‐wise cured resulting in crosslinked HPIM/Poly(BA‐a) NFMs. Structural characterization of as‐electrospun HPIM/(BA‐a) and crosslinked HPIM/Poly(BA‐a) NFM is conducted by FT‐IR spectroscopy to trace the ring opening and crosslinking reactions. Elemental analysis and XPS studies show an increase in carbon content and reduction in nitrogen content due to the crosslinking reaction. Decomposition temperature (T d) of HPIM NFM increases from 218 to 270 °C with the crosslinking based on the DSC. DMA analysis shows that the mechanical strength of the NFMs has increased significantly with crosslinking. Young's moduli of HPIM NFM is increased from 16 ± 7 to 67 ± 1 MPa for crosslinked HPIM/Poly(BA‐a)%33 NFM. Similarly, higher storage modulus is observed for HPIM/Poly(BA‐a) NFMs compared to HPIM NFM. The crosslinked HPIM/Poly(BA‐a) NFMs keep their fibrous morphology after solvent treatment in dimethylformamide revealing their structural stability compared to pristine HPIM NFM.
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    Systematic hydrolysis of PIM-1 and electrospinning of hydrolyzed PIM-1 ultrafine fibers for an efficient removal of dye from water
    (Elsevier, 2017-12) Satilmis, B.; Budd, P. M.; Uyar, Tamer
    In this study, the Polymer of Intrinsic Microporosity (PIM-1) was systematically hydrolyzed in the presence of sodium hydroxide by varying the concentration of base, washing procedure and the time of the reaction. The chemical structure analyses confirmed that PIM-1 could be hydrolyzed by 65% up to 99% conversion depending on the synthesis procedure. The hydrolyzed PIM-1 samples have shown improved solubility which facilitates the fabrication of hydrolyzed PIM-1 ultrafine fibers by electrospinning technique. Extensive optimization studies were performed for the electrospinning of uniform and bead-free fibers from hydrolyzed PIM-1 with different degree of hydrolysis (65%, 86%, 94% and 99%). The electrospun hydrolysed PIM-1 fibrous samples have average fiber diameters (AFD) ranging from 0.58 ± 0.15 μm to 1.21 ± 0.15 μm, depending on the polymer concentration and applied electrospinning parameters. After electrospinning, self-standing hydrolyzed PIM-1 fibrous membranes were obtained which is useful as a filtering material for the adsorption of organic dyes from wastewater. Here, the capability of hydrolyzed PIM-1 electrospun fibrous membranes for the removal of dyes from aqueous solutions was investigated by using a batch adsorption process. The maximum adsorption capacity of fully hydrolyzed PIM-1 fibers was found 157 ± 16 mg g− 1 for Methylene Blue and 4 mg g− 1 for Congo red when the adsorption was conducted by 20 mg L− 1 dye solution without using any dilution. Moreover, maximum dye adsorption was also studied by using concentrated Methylene Blue solutions showing up to 272 mg g− 1 adsorption maximum. In addition, the self-standing fibrous hydrolyzed PIM-1 membrane was employed to separate Methylene Blue from an aqueous system by filtration without the necessity of additional driving force. The results indicate that hydrolyzed PIM-1 electrospun nanofibrous membranes can be a promising filtering material for wastewater treatment