RESUMO
Supported Metal Organic Frameworks (MOFs) with a high specific surface area are of great interest for applications in gas storage, separation, sensing, and catalysis. In the present work we report the synthesis of a novel composite architecture of MOF materials supported on a flexible mat of electrospun nanofibers. The system, based on three-dimensional interwoven nanofibers, was designed by using a low-cost and scalable multistep synthesis protocol involving a combination of electrospinning and low-temperature atomic layer deposition of oxide materials, and their subsequent solvothermal conversion under either conventional or microwave-assisted heating. This highly versatile approach allows the production of different types of supported MOF crystals with controlled sizes, morphology, orientation and high accessibility.
RESUMO
Detection of a single macromolecule based on the use of artificial nanopores is an attractive and promising field of research. In this work, we report a device based on a 5 nm single nanopore with a high length/diameter ratio, tailored by the track etching and atomic layer deposition techniques. The translocation of neutral polyethylene glycol (PEG) and charged polyethylene glycol-carboxylate (PEG-carboxylate) molecules of low molar masses (200 and 600 g mol(-1)) through this nanodevice was studied. It was shown that charged PEG-carboxylate molecules, which permeate through the pore, promote an unusual blockade of ionic current whereas the neutral PEG molecules do not show such behaviour. The molecular dynamics simulation shows that both neutral and charged PEGs permeate through the nanopore close to its inner surface. The main difference between the two macromolecules is the existence of a structured shell of cations around the charged PEG, which is likely to cause the observed unusual current blockade.