Abstract:Mechanochemistry has attracted a lot of attention over the last few decades with a rapid growth in the number of publications due to its unique features. However, very little is known about how mechanical energy is converted into chemical energy. Most of the published works using mechanochemistry neglect the required attention to the experimental parameters and their effect over the resulting products, what makes extremely difficult to reproduce the results from lab to lab. Moreover, if it is taken into consid… Show more
“…On the basis of these first results, we check the existence of a guiding criterion to predict the typology of dynamical regimes on the basis of the relative size of the reactor and the milling body. This represents a contribution on the way towards a unifying parametrization of mechanochemical devices, which could help the reproducibility and the scaling-up of the results of mechanical processing, which are carried out in a plethora of different experimental conditions (Gil-González et al, 2021). We finally investigate systematically the effect of an asymmetric forcing on the milling body dynamics.…”
Understanding the dynamics of milling bodies is key to optimize the mixing and the transfer of mechanical energy in mechanochemical processing. In this work, we present a comparative study of mechanochemical reactors driven by harmonic pendular forcing and characterized by different geometries of the lateral borders. We show that the shape of the reactor bases, either flat or curved, along with the size of the milling body and the elasticity of the collisions, represents relevant parameters that govern the dynamical regimes within the system and can control the transition from periodic to chaotic behaviors. We single out possible criteria to preserve target dynamical scenarios when the size of the milling body is changed, by adapting the relative extent of the spatial domain. This allows us to modulate the average energy of the collisions while maintaining the same dynamics and paves the way for a unifying framework to control the dynamical response in different experimental conditions. We finally explore the dynamical and energetic impact of an increasingly asymmetric mechanical force.
“…They are supported by dislocation and phonon and short-live-active center theories. − In-situ analyses by X-ray powder diffraction and Raman spectroscopy have allowed a complete quantification of the kinetics to understand the chemo-mechanical reactivity . It has also been reported by us and others that some reactions follow zero-order kinetics. − In recent years, different phenomenological models have been applied to ball mill reactions to describe the apparent kinetics of mechanochemical transformations. , In their principles these approaches take into account the very efficient stirring of the powder in the milling vessel leading to a global chemical homogeneity. However, depending on the critical loading conditions (CLCs), the activation of the transformation occurs in a small fraction of the powder which is trapped in the colliding zone of the milling media.…”
The Diels−Alder reaction kinetics between diphenylfulvene and maleimide using mechanochemistry and in liquid state is described. This reaction was carried out in solid state using a modified vibratory ball-mill with temperature control and in solution with toluene as solvent. The effect of temperature, ball mass, material, additives, and aging reaction were studied. We reported for the first time the kinetics of a mechanochemical reaction depending on the ratio ball mass/mass of the reagent. A new kinetic model has been established that corresponds well to our experimental data and allows an estimation of the global activation energy. In solution, the retro Diels−Alder reaction was observed. The reaction was second order for the formation of endo and exo and first order for the retro Diels−Alder reaction. The grinding method shows many advantages compared to solution: shorter reaction time, total reaction, and better selectivity.
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