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This work presents a comparison between electrochemical (Echem), plasma glow, and arc discharge polymerizations of pyrrole doped with iodine to correlate the energy of synthesis, chemical structure, and electrical conductivity of the polymers. Plasma glow discharges were used in the gas phase, electrochemistry in liquid, and arc discharges in a hybrid gas–liquid combination. Polypyrroles had structure and conductivity that varied with the synthesis parameters; Echem produced polymers with high carbonization and without the C≡N triple bonds resulting from the other syntheses. Conductivity divided the polymers in two: those synthesized in liquid were in the 0.01–1.0 S/m range, and those synthesized in gas were in the 10–9–10–7 S/m range, with differences of up to eight orders of magnitude due to the dopants and electrolytes. [ABSTRACT FROM AUTHOR]

The influence of CoOy–CuOx bimetallic particles on the physical and electrical properties of polyfuran (PFu) films to be potentially applied in the absorption of electromagnetic energy in photo-stimulated processes is analyzed in this work. The synthesis of particles was done by sol–gel obtaining spherical profiles with mean size in the 40–120 nm interval and with atomic ratio Cu/Co = 0.57. The synthesis of PFu was done by glow discharge plasmas at 13.56 MHz. The film thickness was obtained in the 10–90 µm interval. Chemical analyses of the polymeric films showed furan groups and others as C–O, C=O and ≈C≈, which can be originated in oxidized and/or fragmented furan rings. The combination of polymer films and metallic particles was done by cryo-lyophilization with ethanol to produce partial solubilization of the polymer to embed the polymeric particles with a mass ratio PFu/CoOy–CuOx = 10. The hybrid composites showed chemical interaction between PFu and the bimetallic particles, suggesting the formation of a new material, which absorbed electromagnetic energy in the visible wavelength interval with activation energy of 2.9 eV, calculated with the Arrhenius equation, with an additive absorption of both, polymeric and metallic fractions. No absorption was detected in the UV region. The electric conductivity was calculated in the 20–100 °C interval, finding that the transference of charges of the hybrid compounds is like that of PFu in magnitude. [ABSTRACT FROM AUTHOR]

Many tokamak devices require a preionization system in order to start up both the discharge cleaning and the main plasma discharge. A stray vertical magnetic field profile of 100 G at the center of the plasma column has been measured on the NOVILLO tokamak by magnetic probes especially made to study the breakdown process. A new vertical field profile, superimposed to the stray field component parallel to the equilibrium field, is created by two additional compensation poloidal coils. Such arrangement of the vertical field profiles, with a 1/R-dependence, has been found optimum to achieve the plasma breakdown without any preionization system. Index Terms--Assisted start-up, magnetic confinement, preionization, stray magnetic fields, tokamak engineering.

Carbonization, oxidation and hydrogenation in expanded polystyrene (EPS) resulted from its thermal degradation at 120 °C are studied in this work using X-ray photoelectron spectroscopy. This hardly biodegradable polymer accumulates large quantities of solid wastes because it is commonly used in disposable dishes and containers. The objective of the work was to obtain a quantitative measure of its thermal degradation at four different depths from the surface, 0, 30, 60 and 90 nm based on the evolution of its chemical states as a function of the heating time. At least ten carbon chemical states were identified, five belonged to the EPS structure, and the others appeared due to the thermal degradation in the form of multiple chemical bonds. The results indicated that carbonization and dehydrogenation were the main degradation mechanisms of the thermal treatment. During the first 7 h of heating, carbonization increased 6.6%, hydrogenation decreased 6.2% and oxidation decreased 2.5%. The surface had more oxidation and behaved differently from the interior of the material. As most atoms in EPS are C, it was considered that the difference in carbonization percentages could represent the degradation percentage of the material. [ABSTRACT FROM AUTHOR]

Traumatic spinal cord injury (TSCI) is a health problem for which there is currently no treatment or definitive therapy. Medicine has explored therapeutic options for patients with TSCI with the aim to improve their quality of life. One alternative has been the development of biomaterials that offer neuroprotection or neuroregeneration of damaged nerve tissue. The microinjection of iodine-doped polypyrrole particles synthesised by plasma (PPPy/I) has shown neuroprotective effects that favour motor function recovery in experimental animals with TSCI. However, their ability to migrate into the tissue has led to the need to test a suspension vehicle that enables the concentration of particles at the site of injury. To achieve this, two biomaterials of PPPy/I (P1 and P2) were studied. The superficial physicochemical characterisation of the polymers was performed by infrared spectroscopy, X-ray photoelectron spectroscopy and contact angle. The rheological performance under oscillatory shear rate of suspensions containing both polymers alone and in combination with bovine serum albumin was also studied. In vivo tests were performed on animals with and without TSCI that were microinjected with particles of P1 or P2 in suspension using a solution of rat serum albumin. Exposure to the protein solutions generates a protein multilayer on the surface of the biomaterials that can drastically change the behaviour of both P1 and P2, which led to severe repercussions in the in vivo assays. The results showed that surface chemistry plays an important role in the performance and that it is possible to treat TSCI with these materials. Graphical abstract: The interaction of the surface of materials PPPy/I.1 (P1) and PPPy/I.2 (P2) with bovine serum albumin (BSA) resulted in a series of changes in the surface chemistry of both biomaterials. The contact angle study (Fig. A) showed the presence of a critical BSA concentration ([BSA]), in which a monolayer was formed on both polymers and then a stable protein multilayer, as evidenced by the establishment of a plateau in the determination of the contact angle. In vivo tests showed that this interaction may be beneficial in the treatment of traumatic spinal cord injury (TSCI), depending on the surface characteristics with or without rat serum albumin (RSA). The TSCI + P1 and TSCI + P2 + RSA groups obtained significant differences in functional recovery compared with the control group according to the Basso, Beattie and Bresnahan scale (BBB). [ABSTRACT FROM AUTHOR]