Filtreler
Fabrication and process optimization of poly(2-hydroxyethyl methacrylate) nanofibers by response surface methodology

Eroglu A.N. | Aydin R.S.T. | Karakeçili A. | Çalimli A.

Article | 2017 | Journal of Nanoscience and Nanotechnology17 ( 1 ) , pp.616 - 625

In this study, Response Surface Methodology (RSM) was used to model and optimize the electrospinning parameters to obtain poly(2-hydroxylethyl methacrylate) (pHEMA) nanofibers which is challenging in terms of evaluating the optimum conditions in nanofiber production. A second order (quadratic model) polynomial function was used for correlation between electrospinning parameters (flow rate, applied voltage, polymer/ethanol concentration) and average fiber diameter. An electrospinning set-up was used to fabricate nanofibers and scanning electron microscopy (SEM) was used to determine the morphology and the size of the nanofibers with . . .diameter ranging from 211 nm to 1661 nm. Results concluded that the concentration of polymer solution played an important role in distribution of fiber diameter. Based on RSM, the optimum pHEMA fibers with 245±35 nm diameter were collected at 13 µL/min flow rate, 12 kV applied voltage at an ethanol:pHEMA ratio of 1.76. Copyright © 2017 American Scientific Publishers All rights reserved Daha fazlası Daha az

Synthesis, characterization and surface properties of amphiphilic polystyrene-b-polypropylene glycol block copolymers

Allı, Abdulkadir | Hazer, Baki | Menceloğlu, Yusuf | Süzer, Şefik

Article | 2006 | European Polymer Journal42 ( 4 ) , pp.740 - 750

The new macroazoinitiators containing poly (propylene glycol), (PPG), with molecular weight 400 and 2000, having hydrophilic character, were synthesized and polymerized with styrene to prepare PS-b-PPG block copolymers. Cast films and e-spun films were prepared and contact angles of these films with water drop were measured to examine hydrophilic/hydrophobic behavior of the copolymers. Each e-spun film with average fiber diameters from 0.25 to 2.20 µm was prepared in N,N-dimethylformamide (DMF) under controlled electrospinning process parameters such as polymer concentration, applied voltage and tip-to-collector distance. Scanning e . . .lectron microscope (SEM) images of the electrospun films were taken to determine the fiber diameters. Surface compositions of the block copolymers were also determined by using an electron spectrometer with Mg K? X-rays. NMR, and FT-IR spectroscopic, and GPC measurements were employed to characterize and determine the PPG contents (6-43%). From the results, electrospinning process increased the hydrophilic properties of the block copolymers obtained, compared their cast film forms. Our results suggest that these polymers are favorable in biological applications in cases where high ratio of the surface to volume and hydrophilicity are required simultaneously. Both chemical structure and topology of the films are important in wetting and hydrophobicity. © 2005 Elsevier Ltd. All rights reserved Daha fazlası Daha az

Solution electrospinning of polypropylene-based fibers and their application in catalysis

Berber, Emine | Horzum, Nesrin | Hazer, Baki | Demir, Mustafa M.

Article | 2016 | Fibers and Polymers17 ( 5 ) , pp.760 - 768

Since the dissolution of polyolefins is a chronic problem, melt processing has been tacitly accepted as an obligation. In this work, polypropylene (PP) was modified on molecular level incorporating poly(ethylene glycol) (PEG) as graft segment (PP-g-PEG) in a range of 6 to 9 mol%. Gold nanoparticles were nucleated in the presence of the copolymer chains via redox reaction. The dissolution of the amphiphilic comb-type graft copolymers containing gold nanoparticles (80 nm in diameter) was achieved in toluene and successfully electrospun from its solution. The diameter of composite fibers was in the range from 0.3 to 2.5 µm. The design . . .of the structurally organized copolymer fiber mats provided a support medium for the nanoparticles enhancing the active surface area for the catalytic applications. The resulting composite fibers exhibited rapid catalytic reduction of methylene blue (MB) dye in the presence of sodium borohydride (NaBH4) compared to corresponding composite cast film. © 2016, The Korean Fiber Society and Springer Science+Business Media Dordrecht Daha fazlası Daha az

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