Mechanochemical synthesis of poly(hydridocarbyne)

Poly(hydridocarbyne) was synthesized by the reaction of bromoform and magnesium metal under the mechanochemical activation conditions.     

Mechanochemical synthesis of poly(butadiene-b-acrylic acid)

The preparation of block copolymer with polybutadiene, respectively poly(acrylic acid) sequences, using mechanochemical methods was investigated. The synthesis involves the generating of polybutadiene macroradicals, by ultra-high speed stirring of the polymer in toluene solution. The macroradicals are capable to initiate the polymerization of acrylic acid present in the reaction medium, leading to block copolymer formation. The influence of different parameters, such as temperature, duration, acrylic acid/polybutadiene molar ratio, on the yield and composition of the synthesized copolymer was studied.     

Mechanochemical synthesis of complex hydrides

This survey concerns the effects of mechanical treatment on the properties of simple and complex hydrides and solid-phase reactions that occur during mechanical activation of hydride systems. Special attention is paid to the mechanochemical synthesis of hydroborates and hydroaluminates.     

Mechanochemical synthesis of some europium diketonates

Results on the influence of mechanoactivation (3–30 min) in a planetary ball mill on the composition, crystal structure, IR spectra and morphology of EuCl₃·6H₂O, dibenzoylmethane (HDBM) and mixtures of EuCl₃·6H₂O — HDBM and EuCl₃·6H₂O — HDBM — 1,10-phenathroline (phen) are presented. Mechanoactivation leads to a decrease of interplanar distances of the EuCl₃·6H₂O and HDBM and partial synthesis of Eu(DBM)₃ and Eu(DBM)₃·phen in the respective mixtures. The fluorescence properties of the products of activation (excitation and emission spectra, lifetime of the excited states) are similar to those of the complexes produced by the conventional “wet” methods, but the strongest excitation of the mechanochemically produced solid state samples is achieved at higher wavelength. Crystals of different forms (prismatic, needle-, long-length-leaf- and rod-like) are formed by mechanoactivation of the mentioned mixtures.     

Polyanilme-montmorilltonite (PANl-MMT) nanocomposites: Mechanochemical synthesis,structure, thermostability and electrical properties

Polyaniline (PANI)-montmorillonite (MMT) nanocomposites were prepared by direct intercalation of aniline molecules into MMT galleries, followed by in situ mechanochemical polymerization under solvent free conditions. X-rays diffraction, Fourier Transform Infra Red analyses and UV-vis spectroscopy confirmed the successful synthesis of polyaniline chains between the MMT nano-interlayers. On increasing the amount of MMT basal spacing decreased gradually, suggesting less intercalation with decreasing amount of aniline. Scanning electron micrographs demonstrated strong differences between the morphologies of PANI-MMT nanocomposites and those of pure MMT and PANI. DC conductivity was measured in the temperature range from 145 K to 303 K using four probe methods. Temperature dependent DC conductivity of PANI and all the PANI-MMT composites followed 3 dimensional variable range hopping (3D VRH) model. Frequency dependent AC conductivity (σ_AC), dielectric constant (ɛ′) and loss factor (ɛ″) have been measured in the frequency range 10²–10⁶. All these measured quantities; σ_AC, ɛ′ and ɛ″ decreased with the increase in MMT content in the composites at all frequencies. The frequency dependence of σ_AC displayed a low frequency region below 10⁴ Hz with almost constant conductivity, while above this frequency a rapid rise in σ_AC was observed with a power law of frequency dependence with an exponent equal to 0.7. Both real and imaginary parts of the permittivity exhibited a low frequency dispersion which has been attributed to hopping of polarons and bipolarons in PANI and its composites. The thermal stability was checked by thermogravimetric analysis (TGA) and was found to be enhanced due to addition of MMT in the PANI.     

Mechanochemical reactions on poly(vynilchloride)

The creep of a rigid material based on poly(vinylchloride) modified with benzidine is studied under tensile stress conditions. Based on the proposed rheological model, the creep equation is derived. The modifications induced by the mechanical stress on some physical properties of the material are studied. The analysis of the facture surfaces shows a brittle character of the fracture, especially in the final stage of the process.     

Mechanochemical synthesis and properties of fullerene derivatives

A technique was developed of mechanochemical synthesis of the fullerene C₆₀ water-soluble derivatives. The derivatives obtained were characterized by elemental analysis, IR spectroscopy, and thermogravimetric analysis. The effect the substances obtained on the mechanical properties of the polyvinyl alcohol films was studied. A strengthening effect of fullerene derivatives on the elastic modulus, tensile strength, and tensile deformation of the polyvinyl alcohol films were found to become apparent already at the concentrations of 0.1–0.2 wt %.     

Mechanochemical synthesis of hemin–imidazole complexes

Solid state reactions of hemin and imidazole were performed by milling the crystalline materials in an agate mortar. The process was monitored by i.r., x.r.d. and Mössbauer spectroscopies. Samples with different hemin to imidazole molar ratios were studied. The interactions of imidazole with the central Fe atom and with the propionic acid groups in the periphery of the hemin molecule were detected. The latter interactions are suppressed by washing with MeOH. Complexes with 1:2 and 1:4 hemin-to-imidazole molar ratios were identified.     

Mechanochemical synthesis of nanosize tin dioxide powders

Structural parameters, dispersity, morphology, and magnetic properties of a tin dioxide-magnetite nanosize composite material mechanochemically synthesized from salt systems were studied. The possibility of using the composite nanopowder as a sorbent for nucleic acids was analyzed.     

Mechanochemical reactions on poly (vinyl chloride)

This paper is concerned with molecular phenomena appearing during deformation of poly(vinyl chloride) under tensile stress conditions. By using indirect techniques (reactions with radical acceptors, with vinylic monomers, electron microscopy) the formation of free radicals, appearing as a consequence of splitting of chemical bonds, is evidenced. The amount of reacted radical acceptor or monomer was proved to be related to solution concentration and to the duration of mechanical stress.     

Mechanochemical activation of minerals on the cordierite synthesis

The cordierite is commonly prepared by reaction of talc, clay and gibbsite within the range of 1200-1350 °C. This study deals with the effect of the amorphization by grinding of that mixture and its influence on the cordierite formation.The mixture previously mentioned underwent six different treatments: mixing without grinding (A) (only mixing); non-amorphizing grinding (A_M) and amorphizing grinding in oscillating mill at four different times (H samples). The phases formed by thermal treatment were studied using differential thermal analysis (DTA)-thermogravimetric analysis (TG)-DTG, dilatometries and X-ray diffraction (XRD) techniques in certain combinations.The thermal analysis of the A and A_M series were compared and they do not show significant differences, whereas the H samples present remarkable alterations in the DTA peaks as well as in the weight losses (TG). Thus, a great number of DTA peaks tend to decrease the temperature of the maximum and to lower the intensity as the amorphization time increases.Calcination tests performed within the range 900-1200 °C show important differences in the diffractograms obtained from the intermediate products. While at 1350 °C the A and H samples reach the same final phases, within the range 1200-1360 °C they present important differences in the DTA indicating that the sequence and direction of reaction are different. The same behavior can be observed by dilatometric analysis.     

Mechanochemical synthesis of thenoyltrifluoroacetone-1,10-phenanthroline europium complex

The paper considers the possibilities for mechanochemical synthesis of rare earth complexes. The complex Eu(TTA)₃·phen (HTTA — 2-thenoyltrifluoroacetone, phen — 1,10-phenanthroline) is synthesized by mechanical treatment of a mixture of EuCl₃.6H₂O, HTTA, phen and NaOH in planetary ball mill Pulverisette 7 for 30 min at 800 min^?1. The non reacted starting reagents and reaction side products are separated by treating activated mixture with water-ethanol solution following a procedure proposed in the literature. The elemental composition, X-ray diffraction pattern, IR spectra, optical properties (excitation and emission spectra, luminescence lifetime) and morphology of the mechanochemically synthesized complex are compared with those of the complex prepared from solution by the conventional method. The results confirm close similarity in the molecular structure and identity of the elemental composition, X-ray diffractograms and fluorescence properties of the compounds prepared by both methods.      

Mechanochemical tools in the synthesis of organometallic compounds

In response to rising environmental concerns, chemistry is experiencing a considerable change in both concepts and practices to adopt more efficient and sustainable technologies. One of the alternative technologies that offer many advantages over the conventional solution-based techniques is mechanochemistry which utilizes mechanical energy to induce chemical reactions. Despite the fact that mechanochemistry has reached high significance in the creation of advanced materials, such as alloys, ceramics, electrode materials, and nanocomposites, in the field of small molecule synthesis its potential remains largely untapped. This review highlights the opportunities and prospects of different mechanochemical tools in the synthesis of organometallic compounds, including transition metal complexes with N-heterocyclic carbene, arene, and cyclopentadienyl ligands, monometallacyclic and pincer derivatives, as well as main group metal compounds (e.g., allyl complexes and the Grignard reagents). Many important organometallic transformations such as C–H bond metalation, transmetalation, and oxidative addition can be successfully implemented under mechanochemical conditions in a highly productive and energy-saving manner. Furthermore, the postmodification of metal-containing species upon grinding or milling is shown to be a powerful route to both new discrete metal complexes and different supramolecular architectures (metal-containing organic cages, macrocylces, networks).     

Mechanochemical synthesis of strontium britholites: Reaction mechanism

The britholites have gained a great interest thanks to their potential applications as matrices for the confinement of the byproducts in the nuclear industry such as minor actinides and long-lived fission products. However, the preparation of britholites requires high temperatures, above 1200 °C. In this work, we strive to prepare these kinds of compounds by a mechanochemical synthesis at room temperature from the starting materials SrF₂, SrCO₃, Sr₂P₂O₇, La₂O₃ and SiO₂ using a planetary ball mill. The obtained results showed that the prepared products were carbonated apatites and the corresponding powders contained some unreacted silica and lanthana. To obtain pure britholites, a heat-treatment at 1100 °C was required. The mechanism involved in the different steps of the reaction is discussed in this paper. The obtained results suggest that the use of raw materials containing no carbonate is expected to directly lead to pure britholites by appropriate milling at room temperature.     

Mechanochemical synthesis of a nitrogen-containing amorphous carbonaceous material

The results of mechanochemical treatment of an amorphous carbonaceous material (ACM) together with urea in a planetary ball mill with ball accelerations up to 60 g are discussed. The common mechanochemical treatment of an AMC and urea is helpful to add up to 2.6 wt % urea to the AMC. X-ray photoelectron spectroscopy indicates that nitrogen can enter the AMC structure in the form of three-coordinated and quaternary nitrogen. The mechanochemical treatment of an AMC together with urea considerably increases the micropore proportion on account of the destruction of larger pores.     

Mechanochemical Synthesis of Poly(germanium and tin organosiloxanes)

The mechanochemical reaction of polyphenylsiloxane with tin and germanium oxides gives rise to soluble tin and germanium phenylsiloxanes. Effect of the nature of the oxide and of the starting reagent ratio on the yield and composition of metal phenylsiloxanes was studied. The reaction products were studied by IR spectroscopy and X-ray phase analysis.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 4, 2005, pp. 610–613.Original Russian Text Copyright © 2005 by Kapustina, Shapkin, Ivanova, Lyakhina.     

Mechanochemical generation of acid-degradable poly(enol ether)s

In an effort to develop polymers that can undergo extensive backbone degradation in response to mechanical stress, we report a polymer system that is hydrolytically stable but unmasks easily hydrolysable enol ether backbone linkages when force is applied. These polymers were synthesized by ring-opening metathesis polymerization (ROMP) of a novel mechanophore monomer consisting of cyclic ether fused bicyclohexene. Hydrogenation of the resulting polymers led to significantly enhanced thermal stability (T_d > 400 °C) and excellent resistance toward acidic or basic conditions. Solution ultrasonication of the polymers resulted in up to 65% activation of the mechanophore units and conversion to backbone enol ether linkages, which then allowed facile degradation of the polymers to generate small molecule or oligomeric species under mildly acidic conditions. We also achieved solid-state mechano-activation and polymer degradation via grinding the solid polymer. Force-induced hydrolytic polymer degradability can enable materials that are stable under force-free conditions but readily degrade under stress. Facile degradation of mechanically activated polymechanophores also facilitates the analysis of mechanochemical products.

A mechanically responsive polymer system that is hydrolytically stable without stress, but unmasks enol ether backbone linkages under force to allow facile hydrolytic degradation.