An advanced structural characterization of templated meso-macroporous carbon monoliths by small- and wide-angle scattering techniques

This study is dedicated to link the nanoscale pore space of carbon materials, prepared by hard-templating of meso-macroporous SiO2 monoliths, to the corresponding nanoscale polyaromatic microstructure using two different carbon precursors wthat generally exhibit markedly different carbonization properties, i.e., a graphitizable pitch and a non-graphitizable resin. The micro- and mesoporosity of these monolithic carbon materials was studied by the sorption behavior of a relatively large organic molecule (p-xylene) in comparison to typical gas adsorbates (Ar). In addition, to obtain a detailed view on the nanopore space small-angle neutron scattering (SANS) combined with in situ physisorption was applied, using deuterated p-xylene (DPX) as a contrast-matching agent in the neutron scattering process. The impact of the carbon precursor on the structural order on an atomic scale in terms of size and disorder of the carbon microstructure, on the nanopore structure, and on the template process is analyzed by special evaluation approaches for SANS and wide-angle X-ray scattering (WAXS). The WAXS analysis shows that the pitch-based monolithic material exhibits a more ordered microstructure consisting of larger graphene stacks and similar graphene layer sizes compared to the monolithic resin. Another major finding is the discrepancy in the accessible micro/mesoporosity between Ar and deuterated p-xylene that found for the two different carbon precursors, pitch and resin, which can be regarded as representative carbon precursors in general. These differences essentially indicate that physisorption using probe gases such as Ar or N2 can provide misleading parameters if to be used to appraise the accessibility of the nanoscale pore space.

An advanced structural characterization of templated meso-macroporous carbon monoliths by small- and wide-angle scattering techniques

This study is dedicated to link the nanoscaled pore space of carbons, prepared by hard-templating of meso-macroporous SiO2 monoliths, to the corresponding nanoscaled polyaromatic microstructure. Two different carbon precursors were used, which generally exhibit markedly different carbonization properties, i.e. a graphitizable pitch and a non-graphitizable resin. The micro- and mesoporosity of these monolithic carbons was studied by the sorption behaviour of a relatively large organic molecule (para-xylene) in comparison to typical gas adsorbates (Ar). In addition, to obtain a detailed view on the nanopore space small-angle neutron scattering (SANS) combined with in-situ physisorption was applied, using deuterated p-xylene (DPX) as a contrast-matching agent in the neutron scattering process. The impact of the carbon precursor on the structural order on an atomic scale in terms of the size and the disorder of the carbon microstructure, on the nanopore structure and on the template process is analysed by special evaluation approaches for SANS and wide-angle X-ray scattering (WAXS). The WAXS analysis shows that the pitch-based monolithic exhibits a more ordered microstructure consisting of larger graphene stacks and similar graphene layer sizes compared to the monolithic resin. Another major finding is the discrepancy in the accessible micro/mesoporosity between Ar and deuterated p-xylene, which was found for the two different carbon precursors (pitch, resin), which can be regarded as representatives in regard to carbon precursors in general. These differences essentially indicate that physisorption using probe gases such as Ar or N2 can provide misleading parameters if to be used to appraise the accessibility of the nanoscaled pore space.

A highly porous metal–organic framework for large organic molecule capture and chromatographic separation

A highly porous metal–organic framework with large pores presents large molecule based applications probed by organic dye molecules.

Death at Number

The five others went first, one by one, and contemporary sources noted how humane the spectacle was, as the participants did not need to see each other. Thousands of Stockholmers had turned out to watch, on this cold day of 30 January 1744, as the last of the six, Gustaf Schedin, accountant at the Insjö copper works, mounted the scaffold. As the culmination of the show, he would be both beheaded and then cut to pieces. The summer before, Schedin had led the fourth Dalecarlian Rebellion: the last march of the free miners and farmers of Dalarna— the mine-rich county 100 miles north-west of Stockholm—to the Swedish capital, in a movement expressing raging discontent with the king, Fredrik I, and his disastrous war with Russia. This sort of thing had been successful before: the fiercely independent-minded people of Dalarna traditionally wielded a certain power, rich as they were in natural resources—the jewel in the crown being the famous Great Copper Mountain mine in Falun. Once it was the largest of its kind in the world, and yielded something like 70 per cent of the world’s copper production. The Falun mine, like many others, was once managed as a cooperative operation, and worked by free miners called mountain-men (bergsmän) with special privileges and laws of their own. But their time was at an end. In 1743 the uprising ended in a bloodbath in Stockholm, and now the six leaders were to be executed. The copper mine was also losing its privileged position. It had given the Swedish kings and queens economic strength for numerous more-or-less successful military adventures down in continental Europe, but was now in decline, and so was the military power of Sweden. This traditionally male activity—becoming angry and getting the lads together to sort things and people out—is chemically related to high levels of the large organic molecule testosterone. For a inorganic chemist inclined to find a good story, it would have been great to now present a direct link between copper and the way we make this molecule in our bodies, starting from cholesterol, claiming that this made the men from Dalarna more inclined to hasty revolutionary actions.

Preparation of Solid and Hollow Asphaltene Fibers by Single Step Electrospinning

Electrospinning has been used to produce micrometer size fibers, both solid and hollow from non-covalently associating small molecules of a low grade hydrocarbon reject of crude oil, asphaltene. Asphaltene defined as a solubility class of crude oil is by no means a polymer but relatively large organic molecule of molecular weight ranging from 500 to 1000 Dalton. The production of asphaltene fibers is feasible by electrospinning because of its unique molecular structure which allows molecular aggregation. Fibers with diameter ranging from 2–20 μm were successfully spun from an asphaltene in toluene solution. Adding 2% hydrogen peroxide enhances electrospinning, leading to formation of hollow fibers, whereas adding 2% water inhibits electrospinning. The structure and morphology of the electrospun fibers were investigated with optical microscopy, scanning electron microscopy, Fourier transform infrared spectroscopy and time-of-flight secondary ion mass spectroscopy. The electrospun asphaltene fibers offer the potential for direct fabrication of membranes without use of multiple synthetic steps, complex electrospinning designs, or post processing surface treatments.