Plant oils: The perfect renewable resource for polymer science?!

Already for a long time, plant oils and their derivatives have been used by polymer chemists due to their renewable nature, world wide availability, relatively low price, and their rich application possibilities. Although many different synthetic approaches have been used, more recent examples are pointing in the direction of catalytic transformations and other efficient reactions to achieve a more sustainable production of polymers from these renewable resources. In this context, olefin metathesis, thiol–ene additions, and other processes can contribute not only to a more efficient synthesis of plant oil based polymers, but also to broaden the application possibilities of plant oils. This feature article provides an overview of the present situation with special attention to the use of olefin metathesis and thiol–ene chemistry as synthetic methods and as polymerization techniques.     

Quinoline‐containing networks from enone and aldehyde triglyceride derivatives

The crosslinking reaction of a triglyceride derivative containing α,β‐unsaturated ketones with diaminodiphenylmethane via aza‐Michael addition has been extensively studied. First, a model study with monofunctional compounds showed that the conjugated addition product undergoes a series of transformations leading to formation of a substituted quinoline. The proposed reaction pathway is presented as a variation of the Skraup‐Doebner‐Von Miller quinoline synthesis. The presence of quinolines as crosslinking points in the cured materials has been proved by means of different characterization techniques, and the properties derived from this aromatization process have been described. This new crosslinking approach has been successfully applied to an aldehyde‐containing triglyceride to obtain quinoline‐containing thermosets. © 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 869–878, 2010     

The deformation of thin aluminium films under helium ion bombardment

ABSTRACT : Aluminium films 2000 Å thick have been bombarded with various flu-ences of 5 keV He⁺ ions and the resulting bubble distribution observed by Transmission Electron Microscopy. Scanning Electron Microscopy of the films indicates an areal increase in the unsupported regions of the films, which, if it results from three dimensional swelling of the films, is two orders of magnitude larger than would be calculated from the total bubble volume as observed by T. E. M. In addition features closely resembling blisters observed in bulk materials, form on the supported regions of the film. These blisters like features are thought to result from lateral stresses in the films.     

Oxidoreductase Catalyzed Polymerization of 3-Methylpyrrole

A one-pot, environmentally friendly enzymatic method is described for the synthesis a polypyrrole derivative, poly(3-methylpyrrole) (poly(3-MP)) in an aqueous solvent system. The enzyme, soybean peroxidase (SBP), was shown to successfully polymerize the beta functionalized pyrrole monomer. The resulting polymer was semiconducting, thermally stable, and exhibited bipolaron absorptions when synthesized in the presence of poly(sodium 4-styrenesulfonate) (PSS). Polymers synthesized in the presence of 10-camphor sulfonic acid (CSA) were found to exhibit slightly higher conductivity values, but were less thermally stable compared to poly(3-MP) polymerized in the presence of PSS. This work should stimulate further interest in expanding the use of enzymes as catalysts for the polymerization of other pyrrole derivatives, as well as other classes of conjugated polymers.     

Synthetic-based aphrons: Correlation between properties and filtrate reduction performance

Aphrons fluids, because of their “noninvasive” characteristic, are indicated for drilling zones that have multiple intercalations of depleted formations adjacent to formations that require high-density fluids. Aphrons are colloidal dispersions containing microbubbles, with cores of gas, liquid or emulsion ranging from 10 to 100 μm in diameter, that are highly stable due to their high interfacial area and multiple surrounding surfactant layers. This paper presents results of physical–chemical properties, bubble size distribution and filtration of systems containing microbubbles. The aphrons were generated by applying a pressure differential under a high-pressure high-temperature (HPHT) filtration cell. Tests were also run with different types of surfactants, specific for generation of bubbles in an organic medium (ester). The surfactants were analyzed for their surface tension and the dispersions produced were photographed under an optical microscope at 60× magnification. The images obtained were digitized to enable determination of the bubble size distribution using an ImageJ program. The filtrate reduction performance of these fluids was determined by static filtration in synthetic porous media. There was a correlation between the filtration characteristics of the fluids, the bubble size distribution and number of bubbles produced in each base and for each surfactant tested. The results obtained served as a reference to formulate a light, non-water-based drilling fluid containing microbubbles with “noninvasive” characteristics.     

Statistical fluctuations for the noise current from random telegraph signals in semiconductor devices: Monte Carlo computer simulations and best fits

Random Telegraph Signals (RTS) has become a major source of variability in the electrical behavior of modern transistors. The major contribution of this work is a new model based on a Monte Carlo algorithm for the mechanisms leading to RTS noise in semiconductor devices. To describe the statistical sample noise current produced by Monte Carlo simulations we experiment with many possible fits using different functions. In order to perform this fitting we follow two distinct approaches: (a) by calculating the sampling moments and by direct substitution in assumed distributions and (b) by performing a non-linear fit using the Levenberg Marquardt algorithm. Our results show a breaking of gaussianity for the nanometer dimensions of deeply scaled technologies, and we show that the ECS peak function is the most appropriate distribution to fit suitably the data for these dimensions. Another relevant contribution is the study of how ballistic effects can change the current distribution. The results indicate an enlargement of the average and variance of the total current when ballistic effects are considered, which are analytically expressed as a function of relevant physical parameters of the semiconductor device.     

Synthesis of the human aldose reductase inhibitor rubrolide L

The first synthesis of rubrolide L, a marine ascidian butenolide and a potent inhibitor of human aldose reductase, has been achieved by two tactically distinct pathways in 4-5 steps and 37-42% overall yield from commercially available 3-chlorotetronic acid.