Nanoparticles Patterned Ceramsites Showing Super-Hydrophobicity and Low Crushing Rate: The Promising Proppant for Gas and Oil Well Fracturing.

An ideal proppant showing super-hydrophobicity and enough strength to bear high closure stress is revolutionary for the effective exploration of gas or oil in shale. Here, the ideal proppants were obtained by wrapping specially treated phenol formaldehyde resins around the cover of the traditional ceramsites. The resin coating is patterned with innumerable fluorine-modified silica nanoparticles, whose thickness is controllable. Benefitting from the low surface energy of fluorine, nano-roughness structures from nano-silica, and the adhesive action of the resin, the modified proppant exhibits awesome properties. The nanoparticle-patterned resin gives the ceramic proppants a water contact angle of 157.8° that has been proved to be stable after being treated in strong acid, thus dramatically accelerating the fracture conductivity for oil by 150% whereas totally preventing water passing through. Besides, it is the resin that reduces the crushing rate of the proppants by 52% and decreases the density of the proppants to 1.63 g/cm³.

Zero-Dimensional Carbon Allotropes-Carbon Nanoparticles Versus Fullerenes in Functionalization by Electronic Polymers for Different Optical and Redox Properties.

Fullerene cages are known as being able to participate in radical initiated copolymerization reactions with vinyl monomers for polymer-functionalized fullerenes. In this work, poly(N-vinylcarbazole) (PVK) was selected as a representative of electronic polymers in the functionalization of fullerene C60 by the same copolymerization reaction to yield the PVK-C60. Similarly found was that small carbon nanoparticles could also participate in the same copolymerization reaction for the nanoparticles to be surface-functionalized and -passivated by the attached PVK polymers, which are structurally adhering to the general definition on carbon dots (CDots), thus PVK-CDots. In the comparison between PVK-CDots and PVK-C60, the former was found to be more absorptive and therefore more effective in photon harvesting across the visible spectral region and also brightly fluorescent, orders of magnitude more so than the latter. Similar to the PVK-C60 and C60 cages in general, the PVK-CDots exhibited significant photoinduced electron accepting characteristics and, at the same time, also extraordinary electron donating abilities that are not available to fullerenes. Because fullerene-based composites with electronic polymers including PVK have found significant applications in optoelectronic devices and systems, the prospect of CDots represented by the PVK-CDots for similar purposes is discussed.

Facile preparation of gadolinium(iii) chelates functionalized carbon quantum dot-based contrast agent for magnetic resonance/fluorescence multimodal imaging.

Suffering from high inherent toxicity generated from heavy metals in semiconductor quantum dots and a complex preparation process, the medical application of conventional gadolinium(iii)/semiconductor quantum dot-based magnetic resonance/fluorescence multimodal imaging (MRI/FI) contrast agent has been limited. In this paper, a new kind of biocompatible carbon quantum dot functionalized by gadolinium(iii) chelates (named as Gd(iii)/CQDs) was obtained through one-step pyrolysis of gadopentetate monomeglumine, which provides simultaneously a carbon source and a gadolinium(iii) source. The Gd(iii)/CQDs show good magnetic resonance response and photoluminescence properties with longitudinal relaxation rate and quantum yield of 5.5-6.4 mM L-1 S-1 [Gd(iii)%, 0.5 mM] and 2.6-8.9%, respectively. The Gd(iii)/CQDs with diameters in the range of 2-3 nm can be well dispersed in deionized water, phosphate-buffered saline buffer solution or culture medium to form a stable dispersion, which with low cytotoxicity can penetrate into cells and show green fluorescence (excitation at 488 nm), presenting a great potential to be used as an MRI/FI contrast agent.