Mehmet Coşkun

A detailed study of thermal degradation of poly(2-hydroxyethyl methacrylate)

The thermal degradation behaviour of poly-2-hydroxyethyl methachrylate and of its deuterium derivative have been studied using thermogravimetry under nitrogen atmosphere, with programmed heating at 10°C/min. At first, the partially degraded polymer has been examined by IR. The cold ring fraction (CRF) was trapped at two ranges from ambient temperature to 340°C and 340–400°C. These CRFs were characterized by IR, 1H, 13C NMR, and GC–MS. When the polymer decomposes thermally at two temperature ranges which are from ambient temperature to 340°C and 340–400°C, at both CRFs, the major product is monomer due to depolymerisation reaction. The side products arising from ester decomposition are a six-membered glutaric anhydride type of ring, an oxolane type of ring, 2-isopropenyl ethyl methacrylate, methacrylic acid and CO2. A mechanism which accounts for all these products has been formulated. The activation energy for the thermal degradation of poly(HEMA) is predicted as 129.8 kJ/mol

Copolymers of phenacyl methacrylate with glycidyl methacrylate: synthesis, characterization and monomer reactivity ratios

Abstract Copolymers with various proportions of phenacyl methacrylate (PAMA) and glycidyl methacrylate (GMA) were prepared by free radical-polymerization in solution in 1,4-dioxane using 2,2′-azobisisobutyronitrile as initiator at 70°C. The polymers were characterized by infrared and 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. The copolymer compositions were determined by 1H-NMR spectra. The reactivity ratios were calculated by both Fineman–Ross and Kelen–Tudos methods. Glass transition and decomposition temperatures of copolymers were determined.

3, 4-Dichlorobenzyl methacrylate and ethyl methacrylate system: monomer reactivity ratios and determination of thermodynamic properties at infinite dilution by using inverse gas chromatography

Abstract Copolymers with various contents of 3,4-dichlorobenzyl methacrylate (BzMA) and ethyl methacrylate (EMA) were prepared in 1,4-dioxane solution using 2,2′-azobisisobutyronitrile (AIBN) as initiator at 60°C. The copolymer compositions were determined by 1H NMR analysis. The monomer reactivity ratios were calculated by both Fineman–Ross, and Kelen–Tudos methods. The monomer reactivity ratios were found to be rBMA=0.521±0.019, rEMA=0.847±0.221 (Kelen–Tudos) and rBMA=0.677±0.008, rEMA=1.117±0.209 (Fineman–Ross). The FT-IR, 13C NMR spectra of the copolymers have been discussed. In all other samples thermal degradation proceeded in a single step. A slight increase in thermal stability of the copolymers was observed with increase in BzMA content. Some thermodynamic quantities such as the specific retention volumes, Vg0, weight fraction activity coefficients of solute probes at infinite dilution, Ω 1 ∞ , Flory–Huggins intereaction parameters, χ12∞, between polymers and solvents, the partial molar free energy, ΔG1∞ the partial molar heat of mixing, ΔH1∞, at infinite dilution were determined from the interactions of poly(BzMA-co-EMA) with alcohols, ketones, acetates, aromatics and n-alkanes by inverse gas chromatography method at 130–150°C. All probes are non-solvent for poly(BzMA-co-EMA) (7:93%) and poly(BzMA-co-EMA) (87:13%) at 130–150°C.

Synthesis and characterization of phenacyl methacrylate – acrylonitrile copolymers and determination of monomer reactivity ratios

Copolymers of phenacyl methacrylate (PAMA) with acrylonitrile (AN) were prepared in 1,4-dioxane solution at 70 °C using 2,2′-azobisisobutyronitrile (AIBN) as initiator. The polymers were characterized by 1H and 13C NMR spectroscopic techniques. Also, solubility parameters, inherent viscosities, average molecular weight and densities of polymers were determined. The copolymer compositions were determined by elemental analysis. The monomer reactivity ratios were calculated by application of conventional linearization methods due to Fineman–Ross and Kelen–Tudős. Thermal properties of the polymers were also studied by thermogravimetric analysis and differential scanning calorimetry. © 2000 Society of Chemical Industry

Thermal degradation of poly [2-(3-chloro-3-methylcyclobutyl)-2-hydroxyethyl methacrylate]

Abstract The thermal degradation of poly[2-(3-chloro-3-methylcyclobutyl)-2-hydroxyethyl methacrylate] [poly(CBHEMA)] has been studied by using thermal volatilisation analysis (TVA) and thermogravimetry (TG). Programmed heating was carried out at 10 °C min −1 from room temperature to 500 °C. Volatile products were separated by subambient TVA and identified by gasphase IR and MS, and GC-MS for volatile liquids. The cold ring fraction and partially degraded polymer have been examined by IR spectroscopy. The monomer was not formed during the degradation since HCl elimination from the chain began at about 150 °C, which is a low temperature for the production of monomer. However, some monomer homologues from the HCl-eliminated polymer were dedected as minor products. The polymer yields carbon monoxide, methane and oxygen as non-condensable products at − 196 °C. Carbon dioxide, hydrogen chloride, water and some unsaturated and saturated hydrocarbons were found in the volatile products. The liquid products of the degradation, the formation of anhydride ring structures and the mechanism of degradation are discussed.

Novel 1-(7-ethoxy-1-benzofuran-2-yl) substituted chalcone derivatives: Synthesis, characterization and anticancer activity

Cancer treatment still requires new compounds to be discovered. Chalcone and its derivatives exhibit anticancer potential in different cancer cells. A new series of benzofuran substituted chalcone derivatives was synthesized by the base-catalyzed Claisen-Schmidt reaction of the 1-(7-ethoxy-1-benzofuran-2-yl) ethanone with different aromatic aldehydes to yield 1-(7-ethoxy-1-benzofuran-2-yl) substituted chalcone derivatives 3a-j. The derivatives were characterized by elemental analysis, FT-IR, 1H NMR and 13C NMR spectroscopy techniques. The anti-growth effect of chalcone compounds was tested in breast cancer (MCF-7), non-small cell lung cancer (A549) and prostate cancer (PC-3) cell lines by the SRB and ATP cell viability assays. Apoptosis was detected by mitochondrial membrane potential, Annexin V staining and caspase 3/7 activity. Formation of reactive oxygen species was determined by DCFDA. The results revealed that chalcone derivatives have anticancer activity with especially chalcone derivative 3a showing cytotoxic effects on cancer cells. In addition, chalcone derivative 3a induced apoptosis through caspase dependent pathways in prostate, lung and breast cancer cells.

Synthesis and characterization of two new cyclobutyl and aryl hydroxyethyl methacrylate monomers and their polymers

Two new hydroxyethyl methacrylates having aryl and cyclobutane rings were synthesized by addition to 1-(epoxyethyl)-3-aryl-3-methylcyclobutane to methacrylic acid. The monomers prepared are 2-(3-methyl-3-phenylcyclobutyl)-2-hydroxyethyl methacrylate (PCHEMA) and 2-(3-methyl-3-mesitylcyclobutyl)-2-hydroxyethyl methacrylate (MCHEMA). Both monomers were polymerized at 60°C in 1,4-dioxane solution using benzoyl peroxide as initiator. Poly(PCHEMA) and poly(MCHEMA) and their monomers were characterized by FT-IR and 1H- and 13C-NMR techniques. Weight average molecular weights of the polymers were determined for poly(PCHEMA) poly(MCHEMA) by gel permation chromatography. Thermal stabilities of the polymers were essentially the same. Glass transition temperatures for poly(PCHEMA) and poly(MCHEMA) were determined as 105 and 137°C, respectively. No changes of the polymers by irradiation with UV light at 254 nm were observed.

Preparation and thermal degradation of poly(p-substituted phenacyl methacrylates)

Abstract The preparation and thermal degradation of two poly(p-substituted phenacyl methacrylates), poly(p-bromophenacyl methacrylate) [poly(BPMA)] and poly(p-methoxyphenacyl methacrylate [poly(MPMA)], are described. The monomers produced from the reaction of corresponding phenacylchlorides with sodium methacrylate, were polymerized with AIBN as initiator. The monomers and their polymers were characterized by IR, 1H and 13C NMR. Thermal degradation of the polymers has been studied using a system consisting of a degradation tube, with a condenser for product collection, a gas phase IR cell and a rotary pump, and by thermogravimetry (TG). Product studies were performed by IR, GC–MS, 1H and 13C NMR. Thermal degradations of these two poly(p-substituted phenacylmethacrylates) to give volatile products, begin at about 250°C. The degradation produces anhydride ring structures in the chain at about 260°C. A mechanism of degradation showing the formation of some products is discussed.

Thermal degradation of poly[3-(1-cyclohexyl) azetidinyl methacrylate]

Thermal degradation of poly[3-(1-cyclohexyl)azetidinyl methacrylate] has been studied using a system consisting of a degradation tube, with a condenser for product collection of a gas phase IR cell and a rotary pump, and thermogravimetry (TG). Product analyses were performed by IR, GC–MS, 1H NMR and 13C NMR. Thermal degradation of the polymer begins at low temperature (about 180°C) by decomposition of azetidinyl ring, producing some amine based products. The degradation produces anhydride ring structures in the chain above about 300°C as a result of a reaction between two neighboring units. A mechanism of degradation showing the formation of some products is discussed.

Synthesis, characterization and thermal degradation of poly[(2-phenyl-1,3-dioxolane-4-yl)methyl methacrylate]

Abstract (2-Phenyl-1,3-dioxolane-4-yl)methyl methacrylate prepared from glycidyl methacrylate and benzaldehyde has been polymerized by benzoyl peroxide. Spectroscopic characterization of the monomer and the polymer has been done by means of Fourier transform infra-red (FTIR) and 1H and 13C nuclear magnetic resonance (NMR) spectroscopies. Also, the techniques of gel permeation chromatography and differential scanning calorimetry have been used in the polymer characterization. Thermal degradation of poly[2-phenyl-1,3-dioxolane-4-yl)methyl methacrylate] has been studied by thermogravimetric analysis and FTIR. Volatile products of the degradation have been investigated by FTIR, 1H and 13C-NMR and gas chromatography-mass spectrometry techniques. The degradation to 270 °C of this polymer gives only the monomer. Side-chain decompositions mainly occur in degradation above 270 °C, including decomposition of the 1,3-dioxolane ring. Total degradation to 500 °C produces many volatile product such as the monomer, benzaldehyde, acrolein, acetone, 2-phenyl-4-hydroxymethyl-1, 3-dioxolane, 4-methylene-2-phenyl-1,3-dioxolane, propene, carbon dioxide and others. A mechanism of degradation showing the formation of some of these products is discussed.