Induced Electronic and Thermal Effects of 86 MeV Nickel Ions in Bisphenol-A Polycarbonate

Bisphenol-A polycarbonate films were irradiated with 86 MeV swift heavy nickel ions at varying fluences, ranging from 1 × 10¹¹ to 1 × 10¹³ ions cm^?2, under vacuum at room temperature, to analyze the induced electrical and thermal modifications. AC conductivity measurements and UV-visible spectroscopy, Fourier transform infra-red (FTIR) spectroscopy, thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), and X-ray diffraction (XRD) techniques were applied to analyze the changes. A significant, exponential increase in conductivity at higher frequency was observed with the increase of nickel ion fluence. UV-visible analysis corroborated the results of the AC conductivity measurement, revealing the increase in size of the carbon clusters embedded in the polymer network, with the increase of heavy ion fluence. FTIR analysis revealed the formation of alkene and alkyne end groups at higher doses, which further supported the suggestion that the variation in electrical properties induced by the ion irradiation of the polymer was due to development of a carbonaceous phase inside the polymer due to the irradiation. Thermal analysis, i.e., TGA and DSC patterns, showed that chain-scission was the leading phenomena in the heavy ion-irradiated polycarbonate samples, resulting in degradation of their thermal stability.     

CHARACTERIZATION OF MELT-MIXED POLY(ETHYLENE-2,6-NAPHTHALATE) (PEN)/POLYCARBONATE (PC) BLENDS

ABSTRACT

Melt blending of poly(ethylene naphthalate) (PEN) and bisphenol A polycarbonate (PC) was performed without the addition of catalyst in a batch mixer at 290°C at various compositions. All the blends prepared exhibited a biphasic character and had very good mechanical properties, in some cases, even better than those of the respective pure constituents. This behavior was attributed to a copolymer formation in the mesophase, which effectively compatibilizes the system. The formation of a PEN/PC block copolymer was considered to be due to transesterification reactions between PEN and PC and was verified by extraction experiments and examination of the soluble and insoluble fractions by various spectroscopic techniques.     

Nickel and Tungsten Bimetallic Nanoparticles Modified Pencil Graphite Electrode: A High-performance Electrochemical Sensor for Detection of Endocrine Disruptor Bisphenol A

In this work, an economically viable, very low cost, indigenous, ubiquitously available electrochemical sensor based on bimetallic nickel and tungsten nanoparticles modified pencil graphite electrode (NiNP-WNP@PGE) was fabricated for the sensitive and selective detection of bisphenol A (BPA). The NiNP-WNP@PGE sensor was prepared by a facile electrochemical one step co-deposition method. The prepared nanocomposite was morphologically characterized by scanning electron microscopy (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), electrochemically by cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The proposed sensor displayed high electrocatalytic activity towards electro-oxidation of BPA with one irreversible peak. The fabricated sensor displayed a wide detection window between 0.025 μM and 250 μM with a limit of detection of 0.012 μM. PGE sensor was successfully engaged for the detection of BPA in bottled water, biological, and baby glass samples.     

Measurement of photoneutron doses in and out of high-energy X-ray beam of a SATURNE-20 medical linear accelerator by ECE polycarbonate detectors

Photoneutron contaminations in and out of high energy X-ray beams of the medical linear accelerator SATURNE 20 (CGR) of the Radiotherapy Department of Omeed Hospital in Isfahan, Iran, have been determined using 250 μm polycarbonate (PC) dosimeters, in strips or in sheets, processed by electrochemical etching (ECE) using specially designed ECE chambers to etch larger sheets. A two dimensional or topographical distribution of neutron contamination was also determined in a full size beam. The neutron dose equivalents (Hn) in the beam of 18 MV X-rays at 80 cm FSD were determined to be linear functions of X-ray dose equivalents (Hx) up to 1400 cSv. The distribution of the Hn at different X-ray doses showed bell-shape profiles with maxima at the isocenter. The ratios of dose equivalents of neutrons to those of X-rays increased as the field size increased having values of 0.22%, 0.28%, 0.31% and 0.37% for field sizes of 10×10, 20×20, 30×30, and 40×40 cm² respectively. Although such neutron dose equivalents can be corrected for patient treatment, it can cause radiation protection problems for workers where the design of the facility is not well planned.     

Dynamic aspects of phase decomposition in reactive blends of polycarbonate and syndiotactic polymethyl methacrylate

Dynamics of phase separation in bisphenol-A polycarbonate (PC)/syndiotactic polymethyl methacrylate (sPMMA) blends has been investigated by means of time-resolved light scattering. Solvent-cast films of the PC/sPMMA blends were transparent, suggestive of miscible character. Several temperature jumps were carried out at a 50/50 PC/sPMMA composition from a homogeneous state (room temperature) into a two-phase regime. The process of phase separation first occurred for some considerable period, then it was followed by phase dissolution driven by chemical reaction. The thermodegradative reaction of sPMMA triggered the dissolution process by probably forming PC/sPMMA graft or random copolymers at the interface, which eventually resulted in a single phase. However, annealing at elevated temperatures for an extended period could lead to cross-linking, and thus a two-phase structure could be fixed permanently. The early stage of spinodal decomposition was interpreted in terms of the linearized Cahn-Hilliard theory. In the late stages of spinodal decomposition, the relationship between scattering peak wavenumber and time was found to obey a power law, but the exponents showed a strong dependence on temperature jumps. The temporal universal scaling failed due to the influence of the chemical reaction. © 1995 John Wiley & Sons, Inc.     

Lactic acid‐ and carbonate‐based crosslinked polymeric micelles for drug delivery

Our objective was to synthesize and evaluate lactic acid‐ and carbonate‐based biodegradable core‐ and core‐corona crosslinkable copolymers for anticancer drug delivery. Methoxy poly(ethylene glycol)‐b‐poly(carbonate‐co‐lactide‐co‐5‐methyl‐5‐allyloxycarbonyl‐1,3‐dioxane‐2‐one) [mPEG‐b‐P(CB‐co‐LA‐co‐MAC)] and methoxy poly(ethylene glycol)‐b‐poly(acryloyl carbonate)‐b‐poly(carbonate‐co‐lactide) [mPEG‐b‐PMAC‐b‐P(CB‐co‐LA)] copolymers were synthesized by ring‐opening polymerization of LA, CB, and MAC using mPEG as an macroinitiator and 1,8‐diazabicycloundec‐7‐ene as a catalyst. These amphiphilic copolymers which exhibited low polydispersity and critical micelle concentration values (0.8–1 mg/L) were used to prepare micelles with or without drug and stabilized by crosslinking via radical polymerization of double bonds introduced in the core and interface to improve stability. mPEG₁₁₄‐b‐P(CB₈‐co‐LA₃₅‐co‐MAC_2.5) had a higher drug encapsulation efficiency (78.72% ± 0.15%) compared to mPEG₁₁₄‐b‐PMAC_2.5‐b‐P(CB₉‐co‐LA₃₉) (20.29% ± 0.11%).¹H NMR and IR spectroscopy confirmed successful crosslinking (～70%) while light scattering and transmission electron microscopy were used to determine micelle size and morphology. Crosslinked micelles demonstrated enhanced stability against extensive dilution with aqueous solvents and in the presence of physiological simulating serum concentration. Furthermore, bicalutamide‐loaded crosslinked micelles were more potent compared to non‐crosslinked micelles in inhibiting LNCaP cell proliferation irrespective of polymer type. Finally, these results suggest crosslinked micelles to be promising drug delivery vehicles for chemotherapy. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2013     

Amorphous structure heat: Heats of solution versus temperature for polysulfone in o-dichlorobenzene

The data presented for polysulfone in o-dichlorobenzene support previous observations on other systems in which the heats of solution decrease linearly with increasing temperature of measurement. Consistent with similar measurements on polycarbonate and polyphenylene oxide, a dramatic slope change from 0.078 cal/g-C° below 120°C to 0.019 cal/g-C° above 120°C occur for the data on polysulfone. The source of these heats is due primarily to the enthalpy difference between the solid polymer and its corresponding liquid amorphous state at the measurement temperature since the heats of mixing are rationalized to be small.     

Detecting organic vapors using a conductometric sensor prepared from Ardel®D-100 and graphite

The composites of graphite with Ardel^?D-100 which is a trademark of a polyester of bisphenol-A with terephthalic and isophthalic acid were used as a sensing material in a conductometric vapor sensor. The magnitudes of responses are increased in the order of benzene, isobutyl acetate, isoamyl acetate, ethyl benzene and chloro benzene. This suggests that Ardel^?D-100 can be used as a sensing material for chlorobenzene, ethyl benzene and isoamyl acetate. On the other hand, specific retention volumes of the sensed vapors on Ardel^?D-100 coated on graphite were determined by inverse gas chromatography at temperatures between 200 and 260 °C. The distribution coefficient, K _s of the vapors between stationary and mobile phases in the column was obtained. It was revealed for the first time that the logarithm of K _s of the solvents varies almost linearly with their responses based on conductometric resistance of the sensing polymer composite. Subsequently, the study suggests that gas chromatographic retention data can be used in prediction of the conductometric responses of a polymeric sensor to vapors. Correspondence: Ferdane Karaman, Department of Chemistry, Yildiz Technical University, 34220 Istanbul-Esenler, Turkey     

Fixation of carbon dioxide into aliphatic polycarbonate,cobalt porphyrin catalyzed regio‐specific poly(propylene carbonate) with high molecular weight

Cobalt porphyrin complex (TPPCo^IIIX) (TPP = 5, 10, 15, 20‐Tetraphenyl‐ porphyrin; X = halide) in combination with ionic organic ammonium salt was used for the regio‐specific copolymerization of propylene oxide and carbon dioxide. A turnover frequency of 188 h^?1 was achieved after 5 h, and the byproduct propylene carbonate was successfully controlled to below 1%, where the obtained poly(propylene carbonate) (PPC) showed number average molecular weight (M_n) of 48 kg/mol, head‐to‐tail content of 93%, and carbonate linkage of over 99%. When the polymerization time was prolonged to 24 h, PPC with M_n over 115 kg/mol and head‐to‐tail linkage maintaining 90% was prepared, whose glass transition temperature reached 44.5 °C. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 5959–5967, 2008     

Photostabilizing of bisphenol A polycarbonate by using UV-absorbers and self protective block copolymers based on resorcinol polyarylate blocks

Bisphenol A polycarbonate degrades due to sunlight, humidity and oxygen. In this study two possible techniques to stabilize the polymer were compared, i.e. blending of UV-absorbers (UVAs) into the polymer or using block copolymers based on resorcinol polyarylates. Combination of different analysis techniques shows that the protection by UVAs is not as good as by the resorcinol polyarylate block copolymers. The block copolymer rearranges itself through a photo-Fries rearrangement within hours into a UV-absorbing top layer. Two different block compositions were studied, and the copolymer with the highest concentration of resorcinol polyarylate groups shows the best protection.