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

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

İncele

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

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

İncele

Barim, Esra; Akman, Feride

Purpose: This study aimed the synthesis and theoretical/experimental characterization of novel benzofuran-based acrylamide monomer. Design/methodology/approach: Novel N-substituted acrylamide monomer, i.e. N-[2–(4-Bromo-benzoyl)-benzofuran-3-yl]-acrylamide (BBFA), was synthesized by reacting (3-Amino-benzofuran-2-yl)-(4-bromophenyl) methanone with acryloylchloride at 0–5oC. Nuclear magnetic resonance (1H-NMR), infrared (FT-IR) and UV-Visible spectrophotometer were used to elucidate the chemical structure of BBFA. Computational studies were performed using the DFT (B3LYP) method on the basis of 6-31 + G (d, p) using Gaussian 09 W and Gauss View 5.0 package in addition to the VEDA program, gauge-independent atomic orbital (GIAO) and time-dependent density functional theory (TD-DFT) methods. Findings: Molecular geometry and vibration assignments of the BBFA monomer were calculated. The molecular structure of the monomer was examined. Both longest and shortest bonds were determined in the structure. The nucleophilic and electrophilic regions of the monomer were determined. The theoretical spectroscopic data of the monomer were compared with the experimental data; both were consistent with each other. The chemical reactivity of the monomer was also determined. Originality/value: The synthesized BBFA monomer can be evaluated in many areas; from medicine to industry (such as textiles) owing to the presence of various active functional groups. Indeed, acrylamide copolymers are remarkable materials for polymer science and industry. The data produced in this study is original and adds to the scientific community.

AtıfScopus5·WoS5·OpenAlex3

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