Recent Developments in Mechanochemical Materials Synthesis by Extrusion

Crawford, Deborah E.; Casabán, José

doi:10.1002/adma.201505352

Cited by 121 publications

(95 citation statements)

References 60 publications

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“…In this regard mechanochemistry can offer significant opportunities as there are already several commercial routes to scaling up including ball-milling and extrusion. 28 Having shown that it is possible to synthesize SCO materials while retaining cooperative properties via mechanochemistry we anticipate that many of the advantages brought by the technique will be exploited in the quest for new, technologically useful smart materials.…”

Section: (F)mentioning

confidence: 99%

Mechanochemical synthesis of cooperative spin crossover materials

Askew

Shepherd

2018

Chem. Commun.

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We describe the synthesis of switchable spin crossover materials via mechanochemistry for the first time. Three chemically diverse spin crossover materials have been produced using solvent-free grinding.Crucially, cooperative spin transition behavior and crystallinity is retained, presenting exciting opportunities for the discovery of new materials with switchable magnetic, optical and structural properties.Spin crossover (SCO) materials have seen a surge in interest in recent years as a result of their optical, magnetic and structural bistability in technologically accessible temperature ranges, giving rise to a number of potential applications in sensing, display and actuator technologies.1,2 The bistability in these systems stems from their propensity to switch reversibly between high-spin (HS) and low-spin (LS) states in response to physical stimuli including temperature, pressure, light irradiation, guest molecules and magnetic field. 3 There are hundreds of known SCO-active materials in the literature including molecular coordination complexes, 1D coordination polymers and 2-/3-dimensional metal organic frameworks. The cooperativity of the SCO phenomenon (abruptness of the transition, hysteretic effects etc.) is a result of electron-phonon coupling between SCO centers in the solid state through elastic interactions in the lattice. 4 The degree of cooperativity is important for application, and has been shown to be sensitive to the crystallinity of the material, particle size and the presence of solvents in the lattice. 2,5 Synthesis of bulk SCO materials has typically been carried out via traditional solution state chemistry, although more complex techniques for the production of nanoparticles and thin films have been developed in the last decade. Remarkably, all existing techniques use solvents and can be timeconsuming; often requiring inert atmospheres and multiple synthetic steps. This aspect is particularly limiting in the search for new SCO-active materials. Herein, we present for the first time the rapid and facile synthesis of three chemically different classes of SCO material, using mechanochemical techniques. We show that microcrystalline samples of SCO-active molecular materials, 1D coordination networks and 3D MOFs can be produced using this technique and crucially the cooperative behaviour of the spin transition is maintained. Finally, we highlight how this technique can be used to accelerate SCO research. Mechanochemistry refers to the reaction of materials through the application of mechanical energy, often through grinding in the solid state. While mechanochemistry has long been used in the synthesis of inorganic materials and composites, in recent years it has also been applied in the synthesis of molecular systems, coordination complexes and frameworks, co-crystals and supramolecular networks. 7,8 Mechanistic explanations for the success of the mechanochemical approach are numerous and as yet no single model can be applied to the varied range of systems that can be produced in this manner....

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Section: (F)mentioning

confidence: 99%

Mechanochemical synthesis of cooperative spin crossover materials

Askew

Shepherd

2018

Chem. Commun.

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“…This has historically involved use in mineral processing, but is becoming increasingly common in the fine chemicals and pharmaceutical industries [1]. Mechanochemical methods have been used in the synthesis and preparation of a broad range of molecules and materials [2][3][4][5]. Many examples are now available where mechanical treatment has been shown to be a method providing access to novel molecular materials or has been used to enhance the selectivity and the rates of product formation [6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

2018

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ABSTARCTMechanochemical methodologies, particularly ball milling, have become commonplace in many laboratories. In the present work, we examine the effects of milling ball mass on the polymorphic conversion of anhydrous caffeine. By investigating a single-phase system, the rate-limiting step of particle-particle contact formation is eliminated. It is found that larger milling balls lead to considerably faster conversion rates. Modelling of the transformation rate suggests that a single, time-independent rate constant is insufficient to describe the transformation. Instead, a convolution of at least two rate-determining processes is required to correctly describe the transformation. This suggests that the early stages of the transformation are governed only by the number of particle-ball collisions. As the reaction proceeds, these collisions less frequently involve reactant, and the rate becomes limited by mass transport, or mixing, even in originally single-phase systems, which become multi-phase as the product is formed. Larger milling balls are less hindered by poorly mixed material. This likely results from a combination of higher impact energies and higher surface areas associated with the larger milling balls. Such insight is important for the selective and targeted design of mechanochemical processes.

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“…The commercially available Fe-MOFs selected in this study (MIL-68, MIL-88A, MIL-100, MIL-127, MIL-101-NH 2 and Fe-BTC) comprise carboxylate linkers that differ both in size and connectivity, in addition to heteroatoms such as N. Therefore, the MOFs show large differences in porosity, thermal stability and heteroatom content, summarized in Table 1 and Figure 1. [17][18][19][20] ), each using different manufacturing technologies, bearing an aspect that is to be investigated. Prices of MOFs are expected to come down and more focus on industrial scale production increases he chances on industrial implementation of MOFs.…”

Section: Introductionmentioning

confidence: 99%

Structural and elemental influence from various MOFs on the performance of Fe@C catalysts for Fischer–Tropsch synthesis

et al. 2017

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The structure and elementary composition of various commercial Fe-based MOFs used as precursors for Fischer–Tropsch synthesis (FTS) catalysts have a large influence on the high-temperature FTS activity and selectivity of the resulting Fe on carbon composites. The selected Fe-MOF topologies (MIL-68, MIL-88A, MIL-100, MIL-101, MIL-127, and Fe-BTC) differ from each other in terms of porosity, surface area, Fe and heteroatom content, crystal density and thermal stability. They are re-engineered towards FTS catalysts by means of simple pyrolysis at 500 °C under a N2 atmosphere and afterwards characterized in terms of porosity, crystallite phase, bulk and surface Fe content, Fe nanoparticle size and oxidation state. We discovered that the Fe loading (36–46 wt%) and nanoparticle size (3.6–6.8 nm) of the obtained catalysts are directly related to the elementary composition and porosity of the initial MOFs. Furthermore, the carbonization leads to similar surface areas for the C matrix (SBET between 570 and 670 m2 g−1), whereas the pore width distribution is completely different for the various MOFs. The high catalytic performance (FTY in the range of 1.9–4.6 × 10−4 molCO gFe−1 s−1) of the resulting materials could be correlated to the Fe particle size and corresponding surface area, and only minor deactivation was found for the N-containing catalysts. Elemental analysis of the catalysts containing deliberately added promoters and inherent impurities from the commercial MOFs revealed the subtle interplay between Fe particle size and complex catalyst composition in order to obtain high activity and stability next to a low CH4 selectivity.

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Recent Developments in Mechanochemical Materials Synthesis by Extrusion

Cited by 121 publications

References 60 publications

Mechanochemical synthesis of cooperative spin crossover materials

Mechanochemical synthesis of cooperative spin crossover materials

The effect of ball mass on the mechanochemical transformation of a single-component organic system: anhydrous caffeine

Structural and elemental influence from various MOFs on the performance of Fe@C catalysts for Fischer–Tropsch synthesis

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