Fatih Biryan

Temperature-frequency dependence on electrical properties of EuCI3 based composites, thermal behaviors and preparation of poly(3-acetamido propyl acrylate)

ABSTRACT The 3-acetamido propyl acrylate [AcAPA] (monomer) was synthesized. The homopolymerization of AcAPA was carried by normal free radical polymerization procedure within tetrahydrofuran at 60 oC using AIBN as the initiator. The poly(AcAPA) composites embedded europium(III)chloride (EuCI3) were prepared. Dependent of temperature and frequency on the dielectric characteristics were investigated in a frequency range starting from 100 Hz to 20000 Hz and in a temperature range from 243 K to 333 K. The results showed that the dielectric loss and dielectric constant increased, and the highest dielectric values were estimated in the case of poly(AcAPA) composites loaded EuCI3 and graphite as well. The FT-IR results indicated that the structural characterization of poly(AcAPA) is strongly affected by the incorporation of EuCI3. Thermal analysis results show that the thermal stability of the EuCI3-doped poly(AcAPA) composites has improved compared to the pure poly(AcAPA). The thermal property of composites has improved significantly due to an increasing in filler loadings showing that a good coordination exists between EuCI3 particles and poly(AcAPA). The dielectric constants of poly(AcAPA)/EuCI3 composites have significantly improved with comparatively low dielectric loss values, indicating that the composites can be considered as a crucial material for embedded capacitor applications. Electrically conducting graphite-based poly(AcAPA)/EuCI3 composites were prepared and the surface morphology of polymer composites were characterized by SEM micrographics. Also, the dc electrical conductivities of graphite-based poly(AcAPA)/EuCI3 were investigated.

Synthesis, structural and thermal characterizations, dielectric properties and in vitro cytotoxic activities of new 2,2,4,4-tetra(4′- oxy-substituted-chalcone)-6,6-diphenylcyclotriphosphazene derivatives

In this study, we aimed to investigate the relationship between the cytotoxic and dielectric properties of newly synthesized 2,2,4,4-tetra(4′-oxy-substituted-chalcone)-6,6-diphenylcyclotriphosphazene derivatives (3–10). Firstly, 2,2,4,4-tetrachloro-6,6-diphenyl cyclotriphosphazene (2) was obtained through Friedel Crafts alkylation in the presence of hexachlorocyclotriphosphazene, benzene and triethylamine and anhydrous AlCl3. The compounds 3–10 were synthesized from the reaction of the hydroxychalcone compounds (1a–h) with 2 in the presence of K2CO3 and within the acetone solvent for the first time and their dielectric constant, dielectric loss factor and ac conductivity of compounds 3–10 were examined through the impedance analyzer as a function of frequency. The in vitro cytotoxic activities of compounds 3–10 in five different concentrations (1, 5, 25, 50, and 100 µM) were analyzed by colorimetric MTT assay which is based on reduction of MTT salt by mitochondria of alive cells over the human ovarian cancer (A2780) and human prostate cancer (PC-3 and LNCaP) cell lines. The LogIC50 values of 3–10 were calculated by using a Graphpad prism 6 programs on a computer. The obtained results suggests that the compounds have a powerful cytotoxic activity (especially A2780, p < 0.05).

Copolymerization of benzyl methacrylate and a methacrylate bearing benzophenoxy and hydroxyl side groups: Monomer reactivity ratios, thermal studies and dielectric measurements

Statistical copolymers of 2-hydroxy-3-benzophenoxy propyl methacrylate (HBPPMA) and benzyl methacrylate (BzMA) in different feed ratios were synthesized by free radical copolymerization method at 60 °C in presence of AIBN initiator. The compositions of copolymer were estimated from 1H-NMR technique. The monomer reactivity ratios of HBPPMA and BzMA were calculated as r1 (rHBPPMA)=0.51±0.076 and r2 (rBzMA)=1.07±0.140 for Kelen-Tüdos method, and was estimated as r1=0.37±0.0006 and r2=0.64±0.0485 according to Fineman Ross equation. The average values estimated from the two methods showed that monomer reactivity ratio of benzyl methacrylate was a slightly high in comparison to HBPPMA. The copolymer system showed an azeotropic point, which is equal to MBzMA=mBzMA=0.43. DSC measurements showed that the Tg’s of poly(HBPPMA) and poly(BzMA) were 84 °C and 73 °C, respectively. The Tg in the copolymer system decreased with increase in benzyl methacrylate content. The decomposition temperature of poly(BzMA) and poly(HBPPMA) occurs in a single stage at about 207 °C and 260 °C, respectively. Those of HBPPMA-BzMA copolymer systems are between decomposition temperatures of two homopolymers. The dielectric constant, dielectric loss factor and electrical conductivity were investigated depend on the frequency of the copolymers. The highest dielectric constants depending on all the studied frequencies were recorded for the poly(HBPPMA) and the copolymer containing the highest HBPPMA unit. The dielectric constant for P(HBPPMA) and P(BzMA) at 1 kHz are 6.56 and 3.22, respectively. Also, those of copolymer systems were estimated between these two values. Similarly, poly(HBPPMA) and copolymers, which are prepared under the same conditions show the dissipation factor and conductivity as well.