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Öğe Carbon Tetrafluoride, Oxygen, and Air RF Plasma Modified Low-Density Polyethylene and Polydimethylsiloxane(Springer, 2023) Polat, Osman; Bhethanabotla, Venkat R.; Ayyala, Ramesh S.; Şahiner, NurettinLow-density polyethylene (LDPE) and polydimethylsiloxane (silicone or PDMS) were exposed to low-pressure air, oxygen (O2), and carbon tetrafluoride (CF4) plasma to modify their surfaces. Plasma power and irradiation time were varied to determine the optimal yield for the water contact angle (θ). For both polymers, the CF4 plasma treatment resulted in the fluorination of the surfaces corroborated by FT-IR and XPS analysis, while small changes in the corresponding θ could be observed. For the O2 and air plasma treatment, the θ values of LDPE were reduced from 100° to around 60°. The changes in surface free energies (SFE) were compared for pre- and post-plasma gas treatment for both polymers and their stability under different aging conditions e.g., air, vacuum, and in water were investigated. The SFE of silicone was increased with the O2 plasma treatment from 10 to 75 mN/m and remained stable in water. Whereas the SFE of LDPE was indifferent to all storing conditions and stable up to 168 h. Also, while the SFE for the CF4 plasma-treated silicone remained almost unchanged, for the LDPE it was decreased to 15 from 35 mN/m. The wettability studies under different conditions e.g., different pH, NaCl, and BSA concentrations affirmed that they can be potentially used for biomedical applications. Finally, the multiple successive gas plasma treatment of LDPE and silicone were done up to 6 times to attain the θ values in the desired range e.g., about 120° to 30° for LDPE and 120° to 13° for silicone.Öğe Force-Based Characterization of the Wetting Properties of LDPE Surfaces Treated with CF4 and H-2 Plasmas(MDPI, 2023) Aktaş, Cihan; Polat, Osman; Beitollahpoor, Mohamadreza; Farzam, Melika; Pesika, Noshir S.; Şahiner, NurettinLow-density polyethylene (LDPE) films are widely used in packaging, insulation and many other commodity applications due to their excellent mechanical and chemical properties. However, the water-wetting and water-repellant properties of these films are insufficient for certain applications. In this study, bare LDPE and textured LDPE (T-LDPE) films were subjected to low-pressure plasmas, such as carbon tetrafluoride (CF4) and hydrogen (H2), to see the effect of plasma treatment on the wetting properties of LDPE films. In addition, the surface of the LDPE film was textured to improve the hydrophobicity through the lotus effect. The LDPE and T-LDPE films had contact angle (θ) values of 98.6° ± 0.6 and 143.6° ± 1.0, respectively. After CF4 plasma treatments, the θ values of the surfaces increased for both surfaces, albeit within the standard deviation for the T-LDPE film. On the other hand, the contact angle values after H2 plasma treatment decreased for both surfaces. The surface energy measurements supported the changes in the contact angle values: exposure to H2 plasma decreased the contact angle, while exposure to CF4 plasma increased the contact angle. Kinetic friction force measurements of water drops on LDPE and T-LDPE films showed a decrease in friction after the CF4 plasma treatment, consistent with the contact angle and surface energy measurements. Notably, the kinetic friction force measurements proved to be more sensitive compared to the contact angle measurements in differentiating the wetting properties of the T-LDPE versus 3× CF4-plasma-treated LDPE films. Based on Atomic Force Microscopy (AFM) images of the flat LDPE samples, the 3× CF4 plasma treatment did not significantly change the surface morphology or roughness. However, in the case of the T-LDPE samples, Scanning Electron Microscopy (SEM) images showed noticeable morphological changes, which were more significant at sharp edges of the surface structures.Öğe Functionalized carbon nanomaterials: Fabrication, properties and potential applications(Elsevier, 2022) Polat, Osman; Gizer, S. Gorkem; Şahiner, Mehtap; Şahiner, NurettinCarbon nanomaterials are particles, generally composed of sp2 and sp3 bonded carbon atoms, that have attracted a lot of interest because of their fascinating properties. Because of the recent advances in nanotechnology, a wide range of nanoscale materials, including carbon nanomaterial allotropes, fullerenes, graphene, graphene oxide, and carbon nanotubes, have been developed to be used in a variety of applications, e.g., electronics, biomedical, energy, catalysis, drug delivery, targeting, and sensors. As significant improvements in physical, chemical, optical, electrical, mechanical, and thermal properties of carbon-based materials are readily achieved, groundbreaking applications of these materials are becoming conventional. Moreover, with the appropriate functionalization, carbon nanomaterials can be modified for multiple specific tasks such as theragnostic applications. These functionalized carbon nanomaterials (FCNMs) can easily be integrated into molecular diagnostic applications, making in vivo applications more comfortable for the patient. This chapter aims to give an overview on the state-of-the-art fabrication, property changes, and potential application of FCNMs summarizing the recent advances that happened in the last few years, especially in theragnostic applications. © 2023 Elsevier Ltd. All rights reserved.Öğe Recent development in solar-driven photocatalytic hydrogen production utilizing g-C3N4(Wiley, 2022) Polat, Osman; Şahiner, NurettinSolar energy is the biggest renewable energy source available with solar thermal power plants, and photovoltaics are already utilized all over the world. Another utilization is the photocatalytic water splitting (PWS) for solar-driven hydrogen (H-2) production to integrate renewable energies into our energy mix and make energy storage and transportation easier. It has the big advantage that H-2, in contrast to electricity, can be stored in an easier manner. In recent years, the research on PWS made major progresses in regard to technology and the photocatalyst material. The goal of this review is to give an overview of the basic ideas of PWS, as well as some methodologies that have been applied in recent years. In particular, sacrificial reagent systems, Z-scheme systems, plasmonic systems, and the use of cocatalysts will be elucidated. In addition, the most recent studies on photocatalytic hydrogen generation utilizing graphitic carbon nitride (g-C3N4), a hot topic in this field, will be discussed.Öğe Recent developments in CO2 capture, utilization, related materials, and challenges(Wiley, 2022) Gizer, Süleyman G.; Polat, Osman; Ram, Manoj K.; Şahiner, NurettinAnthropogenic activities including the combustion of fossil fuels have led to a dramatic increase in the rate of carbon dioxide (CO2) emission in the last three decades. Since fossil-based fuels are still the predominant energy source for this century, CO2 is a colossal problem. It is emitted as a consequence of combustion and human activities and is a major greenhouse gas (GHG) that significantly contributes to climate change and global warming, making CO2 emission a worldwide problem. The Intergovernmental Panel on Climate Change (IPCC) has proposed a 45% decrease in anthropogenic CO2 emissions by 2030, with a target of net-zero CO2 emissions by 2050. Despite its harmful effects, CO2 has the potential to be used for a wide range of different industrial needs, after its capture. CO2 capture technologies are still in the early stage of development because of economic and technological issues. However, in the future, carbon capture and related application technologies and methods may become easier and more accessible due to the new developments in the materials synthesis, strategies and skills and inexpensive utilization, and functioning cost of the employed methods. Furthermore, carbon capture system (CCS) might improve the recent power plan system properties. Concerning climate change, carbon capture is deemed as a promising solution to prevent CO2 emissions. CO2 capture, storage, and utilization are garnering intensive interest from scientists worldwide. This review paper identifies and gave particular attention to the literature on the recent CO2 capture technologies, for example, adsorption, absorption, membrane, and algae-based separation techniques for pre-combustion, oxy-fuel combustion, and post-combustion periods. Aside from all of these capture technologies, the utilization and application of captured CO2 in various industrial fields such as solvents, chemicals, and fuels are evaluated.Öğe The synthesis and characterization of PTCDA-Co(II), and PTCDA-La(III) fluorescent MOFs br(Elsevier Science Sa, 2022) Demirci, Şahin; Gizer, Görkem; Polat, Osman; Ram, Manoj K.; Şahiner, NurettinMetal organic frameworks (MOFs) are unique porous materials with a high surface area employing variety of organic ligands and metal ion components. Moreover, the possibility of developing different additional features, such as magnetic, thermo-responsive, and fluorescent properties that come from the organic ligands and/or metal ions can methodically increase the industrial application of MOF structures. In this paper, perylene 3,4,9,10 tetracarboxylic dianhydride (PTCDA) based MOFs with fluorescent properties were synthesized using Co(II) and La(III) metal ions as nodules. The disappearance of carbonyl group peaks at 1756 cm1 from PTCDA molecules confirmed the synthesis of PTCDA-based Co(II) and La(III) MOFs. The SEM image revealed that the prepared PTCDA-Co(II) MOFs are in ellipsoidal shapes, whereas the PTCDA-La(III) MOFs are in rod or fiber-like shapes. The BET surface area of prepared PTCDA-Co(II) and PTCDA-La(III) MOFs were determined as 125.9 m2/g and 29.9 m2/g, respectively. The prepared PTCDA-based Co(II) and La(III) MOF exhibit fluorescent properties, e. g., upon exposure to 465 nm excitation wavelength, they have fluorescence emission intensity of 10,500 and 13,000 (a.u) at 514 and 510 nm wavelength, respectively. The quenching activity of Cu(II), Ni(II), As(III), and Hg (II) metal ions on fluorescence properties of PTCDA-La(III) MOFs were examined. Moreover, it was observed that the prepared PTCDA-Co(II) and PTCDA-La(III) MOF show 82.9 +/- 0.4 and 95.4 +/- 4.1 % Fe(II) chelating activity at 1400 mu g/mL concentration of PTCDA-Co(II) and PTCDA-La(III). Lastly, Quantum yield was calculated as 52 +/- 1 % for PTCDA-La(III) MOF
