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The combination of well-defined molecular cavities and chemical functionality makes crystalline porous solids attractive for a great number of technological applications, from catalysis to gas separation. However, in contrast to other widely applied synthetic solids such as polymers, the lack of processability of crystalline extended solids hampers their application. In this work, we demonstrate that metal–organic frameworks, a type of highly crystalline porous solid, can be made solution processable via outer surface functionalization using N-heterocyclic carbene ligands. Selective outer surface functionalization of relatively large nanoparticles (250 nm) of the well-known zeolitic imidazolate framework ZIF-67 allows for the stabilization of processable dispersions exhibiting permanent porosity. The resulting type III porous liquids can either be directly deployed as liquid adsorbents or be co-processed with state-of-the-art polymers to yield highly loaded mixed matrix membranes with excellent mechanical properties and an outstanding performance in the challenging separation of propylene from propane. We anticipate that this approach can be extended to other metal–organic frameworks and other applications. Solution processability is required for many industrial processes, but metal–organic frameworks are in general not dispersible, hindering their application. Here, a surface modification is reported that allows porous liquid formation and so synthesis of highly loaded and mechanically robust mixed matrix membranes.

Purpose This paper aims to describe the influence of maleinized linseed oil (MLO), when used as a lubricant, on the thermal and rheological properties of PLA/MWCNTs (polylactic acid/multi-walled carbon nanotubes) and PLA/HNT (halloysite nanotubes) nanocomposites, as a reference for application in 3D printing processes. Design/methodology/approach Nanocomposites were obtained by melting in a twin-screw extruder, mixing PLA with MWCNTs and HNTs in different percentages of 0.5, 0.75 and 1 Wt.% for subsequent mixing by the same process with 5 phr MLO, for application in additive manufacturing, as analyzed by means of differential scanning calorimetry (DSC), capillary rheometry, melt flow rate (MFL) and field emission scanning electron microscopy (FESEM). Findings The results obtained for thermal characterization by using DSC indicate the non-variation of glass transition temperature Tg = 62 ± 2°C and a melting temperature (Tm) around 170°C. Crystallization temperature dropped by approximately 12°C, which should be kept in mind during the transformation processes. The values obtained by capillary rheometry indicate that the material’s viscosity is reduced by the influence of the MLO plasticizer’s lubricant effect on the PLA’s molecular structure. The melt flow index values confirm a rise of approximately 46% in the flow index and back up the capillary rheometry results. The values obtained were as follows: PLA/0.5 Wt.% MWCNT/MLO 5 phr 54.07, PLA/0.75 Wt.% MWCNT/MLO 5 phr 53.46, PLA/1 Wt.% MWCNT/MLO 5 phr 51.84y PLA/0.5 Wt.% HNT/MLO 5 phr 61.8, PLA/0.75 Wt.% HNT/MLO 5 phr 68.3 and PLA/1 Wt.% HNT/MLO 5 phr 71.2 g/10 min. Apart from the nanocharge distribution, the information obtained from the FESEM shows the existence of a cluster, which could have been avoided by more energetic stirring during the nanocompound manufacturing process. Social implications This paper presents an analysis of the insertion of plasticizer in nanocomposites for the application in additive manufacturing processes in fusion deposition modelling (FDM) system. Originality/value This is a novel original research work.

Dry reforming of methane (DRM) involves the conversion of CO2 and CH4, the most important greenhouse gases, into syngas, a stoichiometric mixture of H2 and CO that can be further processed via Fischer–Tropsch chemistry into a wide variety of products. However, the devolvement of the coke resistant catalyst, especially at high pressures, is still hampering commercial applications. One of the relatively new approaches for the synthesis of metal nanoparticle based catalysts comprises the use of metal-organic frameworks (MOFs) as catalyst precursors. In this work we have explored MOF-74/CPO-27 MOFs as precursors for the synthesis of Ni, Co and bimetallic Ni-Co metal nanoparticles. Our results show that the bimetallic system produced through pyrolysis of a Ni-Co@CMOF-74 precursor displays the best activity at moderate pressures, with stable performance during at least 10 h at 700 °C, 5 bar and 33 L·h−1·g−1., Catalysts, 10 (5), ISSN:2073-4344

Covalent postsynthetic modification (PSM) of metal-organic frameworks (MOFs) has attracted much attention due to the possibility of tailoring the properties of these porous materials. Schiff-base condensation between an amine and an aldehyde is one of the most common reactions in the PSM of MOFs. Here, we report the use of the spray drying technique to perform this class of organic reactions, either between discrete organic molecules or on the pore surfaces of MOFs, in a very fast (1-2 s) and continuous way. Using spray drying, we show the PSM of two MOFs, the amine-terminated UiO-66-NH2 and the aldehyde-terminated ZIF-90, achieving conversion efficiencies up to 20 and 42%, respectively. Moreover, we demonstrate that it can also be used to postsynthetically cross-link the aldehyde groups of ZIF-90 using a diamine molecule with a conversion efficiency of 70%.

[Abstract] This work proposes a method based on image analysis and machine and statistical learning to model and estimate osteocyte growth (in type I collagen scaffolds for bone regeneration systems) and the collagen degradation degree due to cellular growth. To achieve these aims, the mass of collagen -subjected to the action of osteocyte growth and differentiation from stem cells- was measured on 3 days during each of 2 months, under conditions simulating a tissue in the human body. In addition, optical microscopy was applied to obtain information about cellular growth, cellular differentiation, and collagen degradation. Our first contribution consists of the application of a supervised classification random forest algorithm to image texture features (the structure tensor and entropy) for estimating the different regions of interest in an image obtained by optical microscopy: the extracellular matrix, collagen, and image background, and nuclei. Then, extracellular-matrix and collagen regions of interest were determined by the extraction of features related to the progression of the cellular growth and collagen degradation (e.g., mean area of objects and the mode of an intensity histogram). Finally, these critical features were statistically modeled depending on time via nonparametric and parametric linear and nonlinear models such as those based on logistic functions. Namely, the parametric logistic mixture models provided a way to identify and model the degradation due to biological activity by estimating the corresponding proportion of mass loss. The relation between osteocyte growth and differentiation from stem cells, on the one hand, and collagen degradation, on the other hand, was determined too and modeled through analysis of image objects’ circularity and area, in addition to collagen mass loss. This set of imaging techniques, machine learning procedures, and statistical tools allowed us to characterize and parameterize type I collagen biodegradation when collagen acts as a scaffold in bone regeneration tasks. Namely, the parametric logistic mixture models provided a way to identify and model the degradation due to biological activity and thus to estimate the corresponding proportion of mass loss. Moreover, the proposed methodology can help to estimate the degradation degree of scaffolds from the information obtained by optical microscopy. Ministerio de Asuntos Económicos y Transformación Digital; MTM2014-52876-R Ministerio de Asuntos Económicos y Transformación Digital; MTM2017-82724-R Xunta de Galicia; ED431C-2016-015 Xunta de Galicia; ED431G/01

Purpose This paper aims to propose using polylactic acid (PLA) as an alternative to nanocomposites in additive manufacturing processes in fusion deposition modelling (FDM) systems and describe its thermal and rheological conditions with multi-wall carbon nanotube (PLA/MWCNT) and halloysite nanotube (PLA/HNT) composites for possible applications in additive manufacturing processes. Design/methodology/approach PLA/MWCNTs and PLA/HNTs were obtained through fusion in a co-rotating twin-screw extruder. PLA was mixed with different percentages of MWCNTs and HNTs at concentrations of 0.5 Wt.%, 0.75 Wt.% and 1 Wt.%. Differential scanning calorimetry (DSC) and capillary rheometry were used to characterise these products, together with an analysis of the melt flow index (MFI). Findings The DSC data revealed that the nanocomposites had a glass transition temperature Tg = 65 ± 2°C and a melting temperature Tm = 169 ± 1°C. The crystallisation temperature of PLA/MWCNTs and PLA/HNTs was between 107 ± 2°C and 129°C, respectively. The viscosity data of PLA/MWCNTs and PLA/HNTs obtained by capillary rheometry indicated that the viscosity of the materials is the same as that of neat PLA. These results were confirmed by the higher fluidity index in the MFI analysis. Originality/value This paper presents an alternative for the applications of nanocomposites in additive manufacturing processes in FDM systems.

Metal-organic frameworks (MOFs) usually require meticulous removal of the solvent molecules to unlock their potential porosity. Herein, we report a novel one-step method for activating MOFs based on the photothermal effect induced by directly irradiating them with a UV-vis lamp. The localized light-to-heat conversion produced in the MOF crystals upon irradiation enables a very fast solvent removal, thereby significantly reducing the activation time to as low as 30 min and suppressing the need for time-consuming solvent-exchange procedures and vacuum conditions. This approach is successful for a broad range of MOFs, including HKUST-1, UiO-66-NH2, ZIF-67, CPO-27-M (M = Zn, Ni, and Mg), Fe-MIL-101-NH2, and IRMOF-3, all of which exhibit absorption bands in the light emission range. In addition, we anticipate that this photothermal activation can also be used to activate covalent organic frameworks (COFs)., This work was supported by the Spanish MINECO (projects PN MAT2015-65354-C2-1-R), the Catalan AGAUR (project 2014 SGR 80), the ERC under the EU FP7 (ERC-Co 615954), and European Union’s Horizon 2020 research and innovation programme under grant agreement No 685727. It was also funded by the CERCA Programme / Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program, under Grant SEV2013-0295. J.E. acknowledges the MINECO for the FPI fellowship.

Here, we report the covalent post-synthetic modification (CPSM) of MOFs using the photothermal effect. Specifically, we subjected mixtures of a photothermally active MOF and another reagent to irradiation with a UV-Vis lamp. This caused the MOF to heat up, which in turn caused the other reagent to melt and subsequently react with the functional groups on the walls of the MOF pores. We have exploited this dual function of MOFs as both heater and host for CPSMs to achieve rapid formation of amides from the reaction of representative MOFs (UiO-66-NH2 or MIL-101-NH2-(Al)) with anhydrides under solvent-free conditions. In addition, this approach enables more complex CPSMs in MOFs such as the formation of amides in UiO-66-NH2 by using an aldehyde through a cascade reaction., This work was supported by the EU FP7 ERC-Co 615954, the Spanish MINECO (project PN MAT2015-65354-C2-1-R), and the Catalan AGAUR (project 2014 SGR 80). It was also funded by the CERCA Programme/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Programme under Grant SEV-2013-0295. J. E. acknowledges the MINECO for the FPI fellowship.

Here we report a method that combines the spray-drying technique with a dynamic covalent chemistry process to synthesize zero-dimensional, spherical and microscale superstructures made from the assembly of imine-based COF nanocrystals. This methodology also enables the integration of other functional materials into these superstructures forming COF-based composites., This work was supported by the Spanish MINECO (project PN MAT2015-65354-C2-1-R), the Catalan AGAUR (project 2014 SGR 80), and the ERC under the EU FP7 (ERC-Co 615954). It was also funded by the CERCA Programme/Generalitat de Catalunya. ICN2 acknowledges the support of the Spanish MINECO through the Severo Ochoa Centers of Excellence Program under Grant SEV-2013-0295

Adsorptive heat transformation systems such as adsorption thermal batteries and chillers can provide space heating and cooling in a more environmental friendly way. However, their use is still hindered by their relatively poor performances and large sizes due to the limited properties of solid adsorbents. Here, the spray-drying continuous-flow synthesis of a new type of solid adsorbents that results from combining metal-organic frameworks (MOFs), such as UiO-66, and hygroscopic salts, such as CaCl2 has been reported. These adsorbents, commonly named as composite salt in porous matrix (CSPM) materials, allow improving the water uptake capabilities of MOFs while preventing their dissolution in the water adsorbed; a common characteristic of these salts due to the deliquescence effect. It is anticipated that MOF-based CSPMs, in which the percentage of salt can be tuned, are promising candidates for thermal batteries and chillers. In these applications, it is showed that a CSPM made of UiO-66 and CaCl2 (38% w/w) exhibits a heat storage capacity of 367 kJ kg−1 , whereas a second CSPM made of UiO-66 and CaCl2 (53% w/w) shows a specific cooling power of 631 W kg−1 and a coefficient of performance of 0.83, comparable to the best solid adsorbents reported so far.

Metal-organic frameworks (MOFs) built up from connecting M-XF6 pillars through N-donor ligands are among the most attractive adsorbents and separating agents for CO2 and hydrocarbons today. The continuous, one-step spray-drying synthesis of several members of this isoreticular MOF family varying the anionic pillar (XF6 =[SiF6 ]2- and [TiF6 ]2- ), the N-donor organic ligand (pyrazine and 4,4'-bipyridine) and the metal ion (M=Co, Cu and Zn) is demonstrated here. This synthetic method allows them to be obtained in the form of spherical superstructures assembled from nanosized crystals. As confirmed by CO2 and N2 sorption studies, most of the M-XF6 -based MOFs synthesised through spray-drying can be considered "ready-to-use" sorbents as they do not need additional purification and time consuming solvent exchange steps to show comparable porosity and sorption properties with the bulk/single-crystal analogues. Stability tests of nanosized M-SiF6 -based MOFs confirm their low stability in most solvents, including water and DMF, highlighting the importance of protecting them once synthesised. Finally, for the first time it was shown that the spray-drying method can also be used to assemble hydrogen-bonded open networks, as evidenced by the synthesis of MPM-1-TIFSIX.

Given the growing request for reusing raw material in new manufactured products in the plastics industry, the present study analyzes the effect of the concentration of recycled materials and pigments on the rheological properties of the polymer blend. It was quantified and analyzed in a statistical way the significance of the effects that these components produce in the rheological properties, such as the melt flow index, the maximum torque and the degradation time on high density polyethylene (HDPE). Knowledge of such properties will optimize processing parameters by using polymer blends with recycled materials and pigments. A minimum effect of the components was evidenced on the melt flow index having the pigment content the greatest impact factor.

Metal–organic frameworks (MOFs) are among the most attractive porous materials currently available. However, one of the challenges precluding their industrial exploitation is the lack of methods for their continuous production. In this context, great advances have been enabled by recently discovered, novel continuous-fabrication methods such as mechanosynthesis, electrochemistry, continuous-flow synthesis and spray-drying. Herein we report the benefits of coupling two of these processes—spray-drying and continuous flow—for continuous synthesis of MOFs assembled from high-nuclearity secondary building units (SBUs). Using the resulting spray-drying continuous flow-assisted synthesis, we have prepared numerous members of diverse MOF families, including the UiO-66, Fe–BTC/MIL-100 and [Ni8(OH)4(H2O)2(L)6]n (where L = 1H-pyrazole-4-carboxylic acid) series. Interestingly, all of these MOFs were automatically obtained as compact microspherical superstructures (beads). We anticipate that our strategy could be easily employed for synthesizing and shaping multivariate (MTV) MOFs.

Modulation of oxide properties in a direction perpendicular to surfaces can be easily achieved by advanced thin film deposition tools. In contrast, simultaneous nanoscale modulation of properties in directions perpendicular and parallel to surfaces, as required for building three-dimensional (3D) nanometric devices, has remained elusive. Though bottom-up approaches allow obtaining controlled lateral growth, these techniques fail to achieve long-range order or do not allow simultaneous modulation of properties in the perpendicular direction. Here, we show that, by exploiting a dual strategy based on the spontaneous surface restructuration of some perovskite substrates and the layer-by-layer growth of nanometric heteroepitaxial perovskite layers, surfaces with laterally modulated surface relief, chemical termination, electrostatic potential, and electrical conductance can be obtained. As illustrative examples, conducting ferromagnetic manganite La2/3Sr1/3MnO3 and ferroelectric BaTiO3 ultrathin films have be...

PMCID: PMC4902134, The exceptional porosity of Metal-Organic Frameworks (MOFs) could be harnessed for countless practical applications. However, one of the challenges currently precluding the industrial exploitation of these materials is a lack of green methods for their synthesis. Since green synthetic methods obviate the use of organic solvents, they are expected to reduce the production costs, safety hazards and environmental impact typically associated with MOF fabrication. Herein we describe the stepwise optimisation of reaction parameters (pH, reagent concentrations and reaction time) for the room temperature, water-based synthesis of several members of the CPO-27/MOF-74-M series of MOFs, including ones made from Mg(ii), Ni(ii), Co(ii) and Zn(ii) ions. Using this method, we built MOFs with excellent BET surface areas and unprecedented Space-Time Yields (STYs). Employing this approach, we have synthesised CPO-27-M MOFs with record BET surface areas, including 1279 m2 g-1 (CPO-27-Zn), 1351 m2 g-1 (CPO-27-Ni), 1572 m2 g-1 (CPO-27-Co), and 1603 m2 g-1 (CPO-27-Mg). We anticipate that our method could be applied to produce CPO-27-Ni, -Mg, -Co and -Zn with STYs of 44 kg m-3 per day, 191 kg m-3 per day, 1462 kg m-3 per day and a record 18720 kg m-3 per day, respectively., This work was supported by the Spanish MINECO (project PN MAT2012-30994) and the EC (project FP7 ERC-Co 61594). I. I. acknowledges the Spanish MINECO for a Ramón y Cajal grant. ICN2 acknowledges support of the Spanish MINECO through the Severo Ochoa Centres of Excellence Program (Grant SEV-2013-0295).

International audience; Dense silicon nitride (SiN) composites with various amounts (0 - 8.6 vol%) of multi-walled carbon nanotubes (MWCNTs) are electrically characterised by combining macroscopic dc-ac and nanoscale conductive scanning force microscopy (C-SFM) measurements. In this way, a coherent picture of the dominant charge transport mechanisms in SiN/MWCNTs composites is presented. A raise of more than ten orders of magnitude in the electrical dc conductivity compared to the blank specimen is measured for MWCNTs contents above 0.9 vol%. Semiconductor and metallic-like behaviours are observed depending on both the temperature and the MWCNTs content. Macroscopic measurements are further supported at the nanoscale by means of C-SFM. The metallic-type conduction is associated to charge transporting along the nanotube shells, whereas the semiconductor behaviour is linked to hopping conduction across nanotube-nanotube contacts and across intrinsic defect clusters within the nanotubes.