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Article Citation - WoS: 1Citation - Scopus: 1PMMA-Based Electrospun Composite Fibers for Dye Adsorption From Water(Sage Publications Ltd, 2025) Cakar, Ilknur; Yesil, Sertan; Bayram, GoknurPoly (methyl methacrylate) (PMMA) and PMMA/poly (ethylene glycol) (PEG)-based composite fibers were produced using electrospinning technique with two different additives; halloysite nanotubes (HNTs) and boron phosphate (BPO4). The effect of the additives on the morphology, wettability and dye adsorption properties of electrospun fibers were investigated by Scanning Electron Microscopy (SEM), water contact angle measurement and UV-VIS spectrophotometry. The results of SEM analysis indicated that addition of PEG resulted in thinner average fiber diameter and beaded structure. Additionally, it was also observed that incorporating both HNT and BPO4 to the PMMA solution caused increased fiber diameter which might be due to increased solution viscosity. For PMMA fibers containing 3 wt% HNT, the highest average diameter and water contact angle were measured as 2204 +/- 302 nm and 110.29 +/- 3.9 degrees, respectively. The produced fibers were tested for the capability to adsorb methylene blue (MB) and methyl orange (MO) from aqueous solutions. Dye adsorption capacity of the samples increased by addition of HNT and BPO4. According to adsorption capacity results, PMMA/PEG/BPO4 composite sample containing 5 wt% BPO4, with an adsorption capacity of 0.76 mg/g, was determined as adsorbent for kinetic and isotherm studies. The adsorption kinetics were well described by the pseudo-second-order model, and equilibrium data were correlated with the Langmuir model.Article Citation - WoS: 6Citation - Scopus: 6Modification of Poly(methyl Methacrylate) Surfaces With Oxygen, Nitrogen and Argon Plasma(Amer Scientific Publishers, 2014) Ozgen, Ozge; Özgen, Özge; Hasirci, Nesrin; Özgen, Özge; Physics Group; Physics GroupPoly(methyl methacrylate) (PMMA) is a strong and lightweight material used in wide range of areas changing from lenses to medical and dental devices. In this study, PMMA samples were modified by oxygen, nitrogen and argon plasma with application of 100 watts 13.56 MHz radio frequency (RF) discharge for different periods (5 min, 15 min and 30 min) and the effects of plasma parameters on surface chemistry, hydrophilicity, surface free energy and topography were examined. XPS analysis showed formation of free carbonyl and carbonate groups by oxygen plasma, carboxylic acid and free carbonyl by argon plasma, and imine, primary amine, amide and nitrozo functional groups by nitrogen plasma treatments. For all cases plasma treatment created more hydrophilic surfaces with lower water contact angles than that of pristine PMMA. Also, plasma caused an increase in the surface free energy and its' polar components determined by Geometric Mean, Harmonic Mean, and Acid-Base approaches. AFM results showed increasing roughness parallel to the duration of plasma. As a result, each plasma treatment caused different functionalities and physical topographies on PMMA surfaces and different functionalities can be used for further developments such as binding specific active molecules to design biosensors or medical devices.Article Citation - WoS: 40Citation - Scopus: 44Surface Characterization and Radical Decay Studies of Oxygen Plasma-Treated Pmma Films(Wiley, 2013) Ozgen, Ozge; Aksoy, Eda Ayse; Hasirci, Vasif; Hasirci, NesrinPolymethylmethacrylate (PMMA) films were modified by RF oxygen plasma with various powers applied for different periods, and the effects of these parameters on the surface properties such as hydrophilicity, surface free energy (SFE), chemistry, and topography were investigated by water contact angle, goniometer, X-ray photoelectron spectroscopy (XPS), and atomic force microscopy, and the types of the created free radicals and their decay were detected by electron spin resonance spectroscopy (ESR). SFE and contact angle results varied depending on the plasma parameters. Oxygen plasma treatment (100 W-30 min) enhanced the hydrophilicity of PMMA surface as shown by decreasing the water contact angle from 70 degrees to 26 degrees. XPS analysis showed the change in the amounts of the present functionalities as well as formation of new groups as free carbonyl and carbonate groups. The roughness of the surface increased considerably from similar to 2 nm to similar to 75 nm after 100 W-30 min oxygen plasma treatment. ESR analysis indicated the introduction of peroxy radicals by oxygen plasma treatment, and the intensity of the radicals increased with increasing the applied power. Significant decrease in radical concentration was observed especially for the samples treated with higher powers when the samples were kept under the atmospheric conditions. As a conclusion, RF plasma, causes changes in the chemical and physical properties of the materials depending on the applied parameters, and can be used for the creation of specific groups or radicals to link or immobilize active molecules onto the surface of a material. Copyright (C) 2012 John Wiley & Sons, Ltd.
