Barim, Esra; Demirelli, Kadir

The poly(4-methacryloyloxyphenyl-4'-methoxystyryl ketone-co-methyl methacrylate) [P(MPMESK0.25-co-MMA)] was synthesized using a free radical copolymerization method at 60 °C. The composition of the copolymer was estimated by 1H-NMR. The nanocomposites of P(MPMESK0.25-co-MMA)-loaded 9 and 11 wt% nanographene (NG) were produced using the ultrasonic homogenizer sonicator. The FT-IR, 1H-NMR, GPC, TGA, XRD, and SEM techniques were used to characterize the copolymer and composites. The thermal behavior of P(MPMESK0.25-co-MMA) partially heated up to 270, 310, 340, and 380 °C was investigated by FT-IR analysis. A six-membered anhydride ring in the copolymer backbone formed at 340 °C and higher temperatures. TG measurements were used to analyze the thermal decomposition processes of pure P(MPMESK0.25-co-MMA) and P(MPMESK0.25-co-MMA)/NG 11 wt% composite. Apparent activation energies for thermal decomposition of P(MPMESK0.25-co-MMA)/NG 11 wt% were determined using the Flynn–Wall–Ozawa (FWO) and Kissinger–Akahira–Sunose (KAS) methods at a temperature range of 200 and 400 °C for a weight loss of approximately 70%. The average activation energies determined from the FWO and KAS methods were 86.3 and 80.3 kJ/mol, respectively. The dielectric and electrical behaviors of the P(MPMESK0.25-co-MMA) and P(MPMESK0.25-co-MMA)/NG 11 wt% composite were investigated at room temperature. The dc activation energy for dc conductivity of nanocomposite was calculated as 1.092 eV. Optical properties such as absorption, reflectance, refractive index, absorption edge, direct band gap of the copolymer, and composites were investigated from their optical examinations in the wavelength region of 200–800 nm. It was found that the optical energy gap values had shifted to the lower energies with the doping of NG.

AtıfScopus1·OpenAlex1

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Barim, Esra; Gundogdu, Emrah

In this study, the P(N-vinyl carbazole-co-benzyl methacrylate) copolymer was synthesized, characterized by FT-IR/1H-NMR spectroscopic methods, and its composition was calculated from 1H NMR spectra. Composites of the copolymer with four different ratios of graphite (GR) and MAX phase (Ti3AlC2) by weight were prepared to obtain functional and novel electronic components for energy storage applications. Scanning electron microscopy, X-ray diffraction analyses were performed for some samples. Differential scanning calorimetry, thermogravimetric analysis curves were used to determine the thermal behavior of the materials. It was concluded that the composite with the highest glass transition temperatures and thermal stability was the composite with 10wt%GR/10wt%MAX additive. The thermal degradation kinetics of the copolymer and the composite containing 10wt%GR/10wt%MAX were investigated by applying the Flynn-Wall-Ozawa (FWO), Kissinger-Akahira-Sunose (KAS) methods and it was found that the thermal degradation activation energy of the composite was lower than that of the polymer. The dielectric properties of the materials were investigated at room temperature and between 0.1 kHz and 5 kHz. At 1 kHz the dielectric constants of the copolymer and 10wt%GR-doped composite were found to be 2.22 and 12.31, respectively. The composites doped with 10wt%GR and 10wt%GR/10wt%MAX were confirmed to be semiconductors.

İncele

Barım, Esra

Bu çalışmada, işlenilebilirlik ve termal kararlılık gerektiren uygulamalar için polimer kompozit malzemeler çalışılmıştır. Aynı zamanda, enerji depolama uygulamaları için dielektrik özellikleri araştırılmıştır. Bu amaçla poli(N-vinil karbazol-ko-etil metakrilat), P(NVC-ko-EMA), kopolimeri serbest radikal polimerizasyonu yoluyla sentezlenmiş, termal ve dielektrik özelliklerini geliştirmek için grafit (GR) ile kompozitleri hazırlanmıştır. Kopolimerin bileşimi 1H-NMR spektroskopisi ile belirlenmiş, yapılan hesaplamalar bileşiminde %56 NVC ile %44 EMA birimlerinin olduğunu ortaya koymuştur. P(NVC0.56-ko-EMA) ve kompozitlerinin DSC analizleri, polimerin 119.98 oC olan camsı geçiş sıcaklığının, grafit eklenmesi ile düştüğünü göstermiştir. TGA analizlerinde, polimere kıyasla grafit katkılı kompozitlerin termal kararlılıklarının daha yüksek olduğu görülmüştür. Hem kopolimerin hem de ağırlıkça %10 grafit içeren kompozitinin termal bozunma kinetiği Flynn-Wall-Ozawa (FWO) ve Kissinger-Akahira-Sunose (KAS) yöntemleriyle incelenmiştir. Hesaplamalar, GR katkılamasının kopolimerin termal ayrışma aktivasyon enerjisi değerini düşürdüğünü göstermiştir. Yapılan dielektrik ölçümlerinde, kompozitlerde artan GR konsantrasyonu ile dielektrik sabiti (Ɛ') ve dielektrik kayıp (Ɛ'') değerlerinin arttığı belirlenmiştir.

İncele

Barim, Esra

In this study, poly(2,2,2-trifluoroethyl methacrylate) homopolymer (PTFEMA) was synthesized via free radical polymerization method, and its composites with graphite oxide (GO) were prepared to improve its dielectric and thermal properties. Thermogravimetric evaluation revealed that graphite oxide acts to limit thermal diffusion throughout the PTFEMA loaded graphite oxide (GO) composite, and hence, thermal stability of composites improved. While the initial decomposition temperature of pure PTFEMA was found to be 233°C from thermogravimetric analysis measurements, the initial decomposition temperature of PTFEMA containing 5 wt% graphite oxide was found to be 251°C. The glass transition temperatures of the composites increased from 76°C to 86°C due to the increase in the amount of graphite oxide added to PTFEMA. The dielectric properties of composites were investigated from 100 Hz to 10 kHz for different temperatures. While the dielectric constant, ε′, of pure PTFEMA at 1 kHz at room temperature was found to be 3.00, that of the PTFEMA containing 5 wt% GO was found 10.32. Therefore, graphite oxide doped PTFEMA composites may be suitable candidates for energy storage applications. The dc conductivity and dielectric loss factor of PTFEMA containing 5 wt% graphite oxide were seen to increase with temperature.

AtıfScopus1·OpenAlex1

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Barim, Esra; Demir, Pınar; Değirmenci, Mustafa; Kirilmiş, Cumhur

The aim of this study was to determine the monomer reactivity ratios, thermal properties and thermal degradation behavior of new P(N-[2-(4-brombenzoyl)-benzofuran-3-yl]-2-methac-rylamide-co-styrene) polymers synthesized at different compositions. For this purpose, novel copolymers of N-[2-(4-brombenzoyl)-benzofuran-3-yl]-2-methacrylamide (NBBM) monomer with styrene (St) monomer were prepared using free radical polymerization method. The 1 H-NMR spectra was used to calculate the compositions of the copolymers. The reactivity ratios of monomers were calculated in line with the universal copolymerization equation using Kelen-Tüdös and Finemann-Ross linearization methods, and found to be r1:0,62 r2:1,09 and r1:0,61, r2:1,07 respectively (where r1 is reactivity ratio of NBBM). DSC, TGA and DTG were used to study the thermal behaviors of the copolymers. The Tg value of P(NBMM) was found to be 211oC and the Tg values of the studied copolymers were determined to increase from 144oC to 184oC with increasing concentration of NBMM units. Thermal data showed that the maximum degradation temperatures increased from 349oC to 391oC as the St units increased in the copolymer system. The activation energy (Ea) values of P(NBBM) and the studied copolymer were determined from the TGA curves obtained at different heating rates and the Flynn-Wall-Qzawa, Kissinger, Tang isoconversional methods were used. Solid state reaction mechanisms were also calculated by being used the Van Krevelen method, a non-isoconversion model. The Ea values obtained with isoconversion models for P(NBBM) and copolymer were found very close to the values obtained from non-isoconversion models. Moreover, the R3 mechanism was proposed for the homopolymer and copolymer.

İncele

Barım, Esra; Torgut, Gülben

The increasing application areas of energy storage devices in recent years make it necessary to produce materials with sufficient efficiency. In this study, composites of poly(2,2,2-trifluoroethyl methacrylate) P(TFEM) homopolymer with nano titanium dioxide (TiO2 NPs) were prepared for applications of these devices requiring thermoelectric properties, and their thermal, dielectric, and electrical properties were investigated. Thermogravimetric analysis showed that TiO2 NPs in all composites limited the thermal diffusion of TiO2 NPs in the polymer matrix and increased the thermal stability of P(TFEM) from 341°C to 361.5°C. As dielectric properties, the dielectric constant (ε′), dielectric loss (ε″), AC conductivity (σac), and real (Z′) and imaginary (Z″) components of impedance of the composites containing TiO2 NPs were evaluated as functions of frequency and different weight percentages of TiO2 NPs. Increases in ε′ and ε″ at up to 15 wt% TiO2 NPs suggested increased dipole polarization. At 100 Hz, the ε″ value of P(TFEM) increased from 3.2 × 10−2 to 1.1 × 10−2, σac increased from 4.98 × 10−10 to 1.00 × 10−8, Z′ increased from 3.67 × 1010 to 8.66 × 1010, and Z″ increased from 2.09 × 108 to 4.42 × 108. Furthermore, ε′, ε″, and impedance decreased with increasing frequency for both P(TFEM) and TiO2 NPs composites, while σac increased with increasing frequency.

AtıfScopus3·OpenAlex5

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Demirelli, Kadir; Barım, Esra; Tuncer, Hülya; Dere, Ayşegül; Canbay, Canan Aksu; Karaduman, Oktay; Al-Sehemi, Abdullah G.; Al-Ghamdif, Ahmed A.; Yakuphanoğlu, Fahretttin

The synthesis of poly[4-(4-vinylbenzyl)oxy)phthalonitrile-co-styrene] [P(VBOPN5 %-co-St)] was carried out by free radical polymerisation at 60 °C. The successful formation of a green coloured single-chain polymer molecule with the formation of cobalt phthalocyanine (SCP-CoPc) was performed at 140–150 °C in the presence of dilute cyclohexanol. The characterization of SCP-CoPc was confirmed by FT-IR and UV/vis spectroscopic techniques. The absorption filtration process of the SCP-CoPc polymer/Sudan III composite was investigated. The introduction of Sudan III into the SCP-CoPc polymer matric strongly affected the optical transmission spectrum of the composite films. The optical transmission measurements of the SCP-CoPc/Sudan III thin film show a high absorption in the visible region (400–800 nm). In the SCP-CoPc/Sudan III composites, the optical band gaps (Eg1 and Eg2) of each of its components has changed significantly. The Eg1 and Eg2 were found to be between 1.90 and 2.83 eV, respectively. Depending on the sudan III content, a wide range from 600 nm to 730 nm indicates complete absorption filtration. The dc electrical conductivity and dielectric behavior of the SCP-CoPc/Nanografene (NG) 6 wt% nanocomposite increased with increasing temperature. From the dc conductivity plot, the Ea values of I. and II. regions were found to be 0.75 eV and 0.27 eV, respectively and it was found that the calculated activation energy obeyed the Arrhenius relationship. The refractive index and the optical permittivity of SCP-CoPc/NG 6 wt% have been estimated.

AtıfScopus2·OpenAlex3

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Demirelli, Kadir; Dere, Ayşegül; Barım, Esra; Tuncer, Hülya; Yakuphanoğlu, Fahrettin

MXene based ternary composite photonic device was fabricated and characterized for the detection of different illuminations. The single chain polymer-cobalt phthallocyanine (SCP-CoPc) carrying metallised pthalocyanine macro ring was used as a polymer for the preparation of ternary composite. The Fourier Transform Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) were used to differentiate MXene/ZnO/SCP-CoPc composite prepared. The presence of Ti, C, O, Zn and Co elements in the structure of the composite was confirmed by EDX. The electrical properties of planar interdigital coated MXene/ZnO/SCP-CoPc (1:1:1 by wt) were investigated for photovoltaic application. The photo-generated carriers contribute to the current flow, and the linear photoconductivity behaviour in current measurements with different illuminations such as 20, 40, 60, 80 and 100 mW/cm2 indicates the possible photo device use of MXene/ZnO/SCP-CoPc nanocomposite. The photocurrent increased from 20 mA/cm2 to 100 mA/cm2 with the light intensity at 0.5 V was tuned from 28 to 280 μA. The forbidden energy gap (Eg) value of the MXene/ZnO/SCP-CoPc ternary composite from optical measurements was found to be 2.36 eV. Experimental results showed that the presence of SCP-CoPc and ZnO (zinc oxide) in the ternary nanocomposite increased the ε' and ε" values of MXene. The ε′ and ε″ of the ternary composite is 13.0, 26217 at 1 kHz and room temperature, respectively. The current-time results suggest that MXene based ternary composite photonic device is a self driven photodevice as the device can detect light without any external voltage bias.

AtıfScopus6·OpenAlex6

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Demirelli, K.; Çelik, A.; Aksoy, Y.; Yegin, M.; Barım, E.; Hanay, Ö.; Hasar, H.

Synthesis of two-dimensional (2D) titanium carbide (Ti3C2Tx), with the name of MXene, by etching Ti3AlC2 (MAX) for different times 20 (v/v) % hydrofluoric acid (HF) at 40 °C was carried out. The influences of time, temperature and source of MAX on the synthesis of MXene were researched. The MXenes produced were characterized by fourier-transform ınfrared (FT-IR) spectroscopy technique, energy dispersive x-ray spectroscopy (EDX), scanning electron microscopy (SEM), x-ray diffraction (XRD) and thermogravimetry (TG) instruments. Above 390 °C, MXene layers were considerably oxidizing and forming anatase and rutile phases of TiO2 under air atmosphere. The resistance of MAX and MXene was 3.6 Ω and 116 Ω, respectively. However, the resistance of the residual part of MXene heated to 620 °C considerably increased to 17850 Ω. This behavior is another important piece of evidence showing that the MXene crystal structure has changed significantly and transformed into a new chemical structure containing anatase and rutil titanium oxide (TiO2). The dielectric loss (ϵ’’) and alternating conductivity (δac) of the MAX and MXenes were determined from their impedance measurements. The ϵ’’ and δac values of MXene were compared with those of MAX. Direct curent conductivities of MAX and MXene produced for 24 h were found to be 0.016 S/cm and 0.0023 S/cm, respectively.

AtıfScopus12·OpenAlex11

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Demirelli, Kadir; Barim, Esra; Çelik, Aytekin; Yegin, Mustafa; Aksoy, Yunus; Hanay, Özge; Hasar, Halil

The Ti3C2Tx MXene nanosheet was prepared by 40% (v/v) hydrofluoric acid etching at 20 °C for 48 h and delamination of bulk MAX Ti3AlC2 precursor material. A 2D nanomaterial MXene Ti3C2Tx as a nanofiller was introduced to polysulfone (PSulfone) matrix. MXene and PSulfone/MXene nanocomposite systems were characterized by X-ray diffraction, scanning electron microscopy, transmission electron microscope, Fourier-transform infrared and thermogravimetric analysis instruments. Dielectric and electrical characterization of PSulfone/MXene nanocomposite was carried out. The electrical resistance of Ti3C2Tx MXene from measurement current (I)–voltage (V) was measured as 116 Ω. Pure PSulfone matrix exhibits typical insulator behavior, and MXene exhibits a good conductor behavior. But, when MXene was added to the pure PSulfone matrix, the resistance of the MXene/PSulfone nanocomposite increased moderately compared to that of pure MXene. In spite of the excess of surface functional groups, MXene showed surprisingly good electron transport across the surface, while in the case of PSulfone/MXene nanocomposite, the insulating behavior of PSulfone significantly reduced the electron transport of MXene. The semiconductor behavior of PSulfone/Ti3C2Tx MXene nanocomposite indicates that MXene provides efficient charge carrier transfer in the nanocomposite system. By comparing the TGA results between the PSulfone and different weight ratios of PSulfone/Ti3C2Tx MXene nanocomposites, it was determined that MXene nanosheets had a significant effect in slightly accelerating the thermal degradation of PSulfone. Optical conductivity was investigated by preparing a film of PSulfone/MXene nanocomposite on an interdigital contact. It was observed that the optical current values changed depending on the increasing illumination intensity. Considering current–voltage measurements, the photocurrent generation potential of PSulfone/MXene nanocomposite shows that it can be used in photodevice production.

AtıfScopus24·OpenAlex27

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