The extreme instability and strong chemical activity of carbyne, the infinite sp 1 hybridized carbon chain, are responsible for its low possibility to survive at ambient conditions. Therefore, much less has been possible to explore about carbyne as compared to other novel carbon allotropes like fullerenes, nanotubes and graphene. Although end-capping groups can be used to stabilize a carbon chain, length limitation is still a barrier for its actual production, and even more for applications. Here, we report on a novel route for bulk production of record long acethylenic linear carbon chains protected by thin double-walled carbon nanotubes. A corresponding extremely high Raman band is the first proof of a truly bulk yield formation of very long arrangements, which is unambiguously confirmed by transmission electron microscopy. Our production establishes a way to exceptionally long stable carbon chains, and an elegant forerunner towards the final goal of a bulk production of essentially infinite carbyne.Different kinds of allotropes can be formed from elemental carbon due to its sp n hybridization 1 . 1 arXiv:1507.04896v2 [cond-mat.mtrl-sci]

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Toughness is crucial to the structural function of bone. Usually, the toughness of a material is not just determined by its composition, but by the ability of its microstructure to dissipate deformation energy without propagation of the crack. Polymers are often able to dissipate energy by viscoplastic flow or the formation of non-connected microcracks. In ceramics, well-known toughening mechanisms are based on crack ligament bridging and crack deflection. Interestingly, all these phenomena were identified in bone, which is a composite of a fibrous polymer (collagen) and ceramic nanoparticles (carbonated hydroxyapatite). Here, we use controlled crack-extension experiments to explain the influence of fibre orientation on steering the various toughening mechanisms. We find that the fracture energy changes by two orders of magnitude depending on the collagen orientation, and the angle between collagen and crack propagation direction is decisive in switching between different toughening mechanisms.

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Silica monoliths exhibiting a unique hierarchical network structure with a bimodal pore size distribution and high surface areas were prepared from three different glycol-modified silanes by sol−gel processing. Tetrakis(2-hydroxyethyl)-, tetrakis(2-hydroxypropyl)-, and tetrakis(2,3-dihydroxypropyl)orthosilicate were obtained by transesterification reaction from tetraethylorthosilicate and the corresponding alcohols. The present work shows that, for ethylene glycol- and propane-1,2-diol-modified silanes, simply the release of the corresponding diols during sol−gel processing in the presence of block copolymeric surfactants such as Pluronic P123 results in phase separation on different levels. In addition to an extraordinary cellular network structure with interconnected macropores of several hundreds of nanometers in diameter, the material exhibits a well-ordered mesostructure with periodically arranged mesopores of about 6−7 nm in diameter. Interestingly, the application of glycerol-modified silanes at the given synthesis conditions results in the formation of a disordered silica mesostructure. The architectural properties and the morphology of the gel network cannot only be controlled by the choice of the glycol but also by the amount of acid catalyst in the starting composition.

Graphical abstractHighlights► The size of amorphous SiO2 nanoparticles coincides for different test methods. ► Different measurement methods deliver different values for crystalline ZrO2 nanoparticles. ► The use of complementary methods is favourable.

The verification of a successful covalent functionalization of graphene and related carbon allotropes can easily be carried out by Raman spectroscopy. Nevertheless, the unequivocal assignment and resolution of individual lattice modes associated with the covalent binding of addends was elusive up to now. Here we present an in situ Raman study of a controlled functionalization of potassium intercalated graphite, revealing several new bands appearing in the D-region of the spectrum. The evolution of these bands with increasing degree of functionalization from low to moderate levels provides a basis for the deconvolution of the different components towards quantifying the extent of functionalization. By complementary DFT calculations we were able to identify the vibrational changes in the close proximity of the addend bearing lattice carbon atoms and to assign them to specific Raman modes. The experimental in situ observation of the developing functionalization along with the reoxidation of the intercalated graphite represents an important step towards an improved understanding of the chemistry of graphene.