RSC Mechanochemistry最新文献

Unlike conventional modes of activation of reactivity, mechanochemical force provides facile and unique pathways. Extensive studies have been performed on the thermal and photochemical interconversions between benzene and its valence isomers. In this article, we show that mechanochemical pulling along 1,2- positions of triprismane (TP) can precisely control the outcome, namely, benzene (BZ) and/or Dewar benzene (DB), depending upon the strength of external force. Within the force range of 1.5–1.9 nN, DB is formed exclusively, whereas at forces exceeding ≥2.0 nN, BZ becomes the major product. Also, we report that on pulling across 1,4-sites of TP, BZ is produced exclusively when external force ≥1.8 nN. Ab initio steered molecular dynamics (AISMD) simulations on the force modified potential energy surfaces (FMPESs) for 1,2-pulling of TP reveal that DB becomes the minor product beyond external force ≥2.0 nN. The thermodynamically controlled product, BZ, is obtained as the major and sole product for stronger 1,2-pulling and 1,4-pulling respectively. The constrained geometries simulate external force (CoGEF) calculations fail to locate the kinetically trapped intermediate, DB, revealing the prowess of AISMD in revealing unique intermediates and fleetingly stable products in the course of mechanochemical reactions. Also, we demonstrate that the TP → BZ reaction, which demands significant thermal energy, can be induced mechanochemically.

In the present work, we report a sustainable, room-temperature mechanochemical approach for synthesizing functional silicon quantum dots (Si QDs) with tunable photoluminescence (PL) in the visible range. Using hydrogen silsesquioxane as a precursor, precise control over the size and surface chemical state of Si QDs is achieved through controlled ball-milling and subsequent chemical etching and hydrosilylation. Discrete element method simulations reveal that the cumulative supra-critical impact energy (E_sup), defined as the total impact energy exceeding a critical threshold (e_crit) required for chemical activation, plays a dominant role in driving the formation of Si radicals and Si–H bond cleavage, which are key steps in crystallite growth. Under high-energy milling conditions using larger balls, a significant portion of collisions exceed e_crit, thereby enhancing the efficiency of solid-state chemical reactions and leading to the formation of larger Si QDs. The PL red shift observed across blue-, green-, and red-emitting Si QDs is attributed to a size–surface coupling mechanism. For smaller Si QDs, PL originates from quantum-confined band-edge transitions and shallow surface states, enabled by high alkyl chain coverage. Larger Si QDs exhibit red-shifted, excitation-independent emission dominated by deep oxide-related surface states, stemming from enhanced oxidation and reduced organic passivation. These findings highlight the interplay between mechanical energy input, structural/size evolution, and surface chemistry in tailoring the optical properties of Si QDs.

The mechanochromic properties of polymer particles crosslinked by difluorenylsuccinonitrile (DFSN), a radical-type mechanochromophore, are reported in relation to particle size and glass transition temperature. DFSN-crosslinked nanoparticles and microparticles were prepared via emulsion polymerization and suspension polymerization of vinyl monomers, respectively, using a DFSN-containing crosslinker. Mechanical grinding of the prepared white particles induced a pink coloration, originating from cyanofluorenyl (CF) radicals generated by the mechanically induced homolysis of DFSN units within the particles. The mechanochemical response of the particles was evaluated using scanning electron microscopy and electron paramagnetic resonance spectroscopy, revealing that microparticles exhibited a stronger response than nanoparticles due to the differences in pulverization behavior. The mechanochemical response also showed a strong correlation with the glass transition temperatures of the particles, highlighting the importance of polymer chain mobility in the mechanochromic properties of the developed polymer particles.

Correction for ‘Mechanochemical kilogram-scale synthesis of rac-ibuprofen:nicotinamide co-crystals using a drum mill’ by Jan-Hendrik Schöbel et al., RSC Mechanochem., 2025, 2, 224–229, https://doi.org/10.1039/D4MR00096J.

Correction for ‘Utilizing an attritor mill for solvent-free mechanochemical synthesis of rac-ibuprofen:nicotinamide co-crystals’ by Sarah Triller et al., RSC Mechanochem., 2025, 2, 538–543, https://doi.org/10.1039/D5MR00020C.

We report an efficient photo-contact electrification (CE) method for controlling the synthesis of pristine silver nanoparticles of different shapes, as one, two, and three-dimensional materials, notably rods, spicules and triangles. This uses a vortex fluidic device (VFD) which houses a rapidly rotating quartz tube tilted at 45° while the aqueous silver nitrate thin film is irradiated at 254 nm. The photo-CE associated with the mechanical energy imparted into the liquid in the microfluidic platform allows control of the size and shape of the nanoparticles, and some micron size particles, depending on the rotational speed of the tube and concentration of silver nitrate. Uniform shapes are generated with pristine surfaces in the absence of added reducing agents, with processing scalability under continuous flow. This synthetic method is also simple and cost-effective, and overall adheres to the principles of green chemistry.

The growth of tribofilms from the mechanochemical decomposition of lubricant additives is crucial to prevent wear of sliding metal surfaces. For some applications, such as electric vehicles and wind turbines, lubricants can be exposed to electric fields, which may affect tribofilm growth. Experimental tribometer results have shown conflicting results regarding antiwear tribofilm growth and wear under external electric potentials. Moreover, the effect of electric fields on the mechanochemical decomposition of lubricant additives remains unclear. Here, we use nonequilibrium molecular dynamics (NEMD) simulations to study the mechanochemical growth of a polyphosphate tribofilm from trialkyl phosphate molecules under external electrostatic fields. The decomposition rate of phosphate esters increases exponentially with the applied stress and temperature. The electric field generally accelerates the molecular decomposition, both by enhancing the interfacial stress and reducing the steric hindrance for nucleophilic substitution. The Bell model is used to analyse the electro-, mechano- and temperature-dependent decomposition process. Under weak electric fields, the activation energy for molecular decomposition increases due to the competition between electric field- and shear-induced deformations. For stronger fields, the activation energy decreases linearly with increased electric field strength and this dominates over the shear-induced molecular rotation. The resultant non-monotonic variation in the activation energy for molecular decomposition with electric field strength explains the conflicting effects of electric potential on tribofilm growth observed experimentally. The activation volume decreases linearly with increasing electric field strength, indicating a reduced dependence of the decomposition on shear stress as the electric field dominates. Asymmetric tribofilm growth is observed between surfaces with external electric fields, which is consistent with the experimental observations. This study presents atomistic insights for the coupling of electro- and mechano-catalysis of an industrially-important molecular decomposition process.

This work proposes the construction of chemical models based on the Gibbs composition triangle, which provides support for the proper interpretation of semiconductor synthesis under non-equilibrium processing, considering the pertinent variables of the system. It demonstrates how chemical models are constructed using experimental findings and theoretical insights and by incorporating data available in the literature. Then, an illustrative example is used to validate the construction, interpretation and application of a chemical model for obtaining PbTe via non-equilibrium process. This approach can be directly applied to forecast the formation of IV–VI and II–VI binary semiconductors, as well as the formation of ternary semiconductor solid solutions. However, it is exemplified—in this work—via the mechanochemical synthesis of PbTe. This work aims to construct a chemical model that maps the transformation from precursors to semiconductor material through the high-energy milling process.

The insertion of force-active molecules (mechanophores) with optical-switching properties into polymer chains has enabled the development of various mechanochromic polymers. Among them, colorimetric spiropyran (SP) has been the most extensively studied. However, the low extent of SP activation in bulk materials and the associated poor material mechano-sensitivity have hindered its broader applications. To address this challenge, we report the amplification of SP mechanophore activation in bulk materials through a tethering design. Two SP mechanophores were tethered through a long aliphatic linker, and the resulting molecule was employed as a crosslinker in silicone elastomer networks. This approach resulted in an enhancement of SP activation by more than twofold compared to its mono-SP counterpart. Additionally, we observed that increasing the number of added short linkers leads to greater tension constraints on these linkers, creating a self-reinforcing effect on mechanophore activation. We anticipate that this tethering strategy can be adapted to other non-scissile mechanophores in bulk studies.

Understanding the degradation mechanisms of perfluoropolyether (PFPE) lubricants is critical for the reliability of Heat-Assisted Magnetic Recording (HAMR) systems. In this study, we conducted ReaxFF reactive molecular dynamics simulations to investigate the role of diamond-like carbon (DLC) surfaces in PFPE degradation under confined shear and at elevated temperature. The results show that confined shear plays a more dominant role than temperature, with the decomposition rate constant increasing with shear velocity. PFPE degradation primarily initiates through C–OH bond rupture at end groups, typically after the OH group bonds to the DLC surfaces. Bonded PFPE molecules adopt bridge and loop conformations, both contributing comparably to degradation with increasing shear velocity, with bridges being slightly more sensitive to shear. Our analysis suggests that bridge dissociation is facilitated by shear-induced end-to-end stretching, while loop dissociation is driven by entanglement of conformationally flexible main chains. These insights provide guidance regarding further development of reliable HAMR systems.