Mechanochemical complexation products

As with the products of polycondensation, the products of mechanochemical complexation were characterized by analysis of chemically linked nitrogen by ligand synthesis (Kjeldahl method), elementary analysis, and IR spectroscopy. The nitrogen variance for different working conditions is discussed elsewhere in this paper results of the elementary analysis are in Table III. IR spectra confirm that the ligand has the same structure as the polycondensation products, obeying the rule that for short durations, the band for ester carbonyl remains unaltered. For longer times, this band disappears. 

The mechanochemical treatment by ball milling is a very complex process, wherein a number of phenomena (such as plastic deformation, fracture and coalescence of particles, local heating, phase transformation, and chemical reaction) arise simultaneously influencing each other. The mechanochemical treatment is a non-equilibrium solid-state process whereby, the final product retains a very fine, typically nanocrystalline or amorphous structure. At the moment of ball impact, dissipation of mechanical energy is almost instant. Highly excited state of the short lifetime decays rapidly, hence a frozen disordered, metastable strucmre remains. Quantitative description of the mechanochemical processes is extremely difficult, herewith a mechanochemical reaction still lacks clear interpretations and adequate paradigm. 

Mechanochemical reactions are extremely complex, thereby not fully understood. The reason for this probably lies in the fact that the whole numbers of elementary processes throughout the mechanical energy may be dissipated. However, the accumulation of a large number of results published enables, at least tentatively, some generalizations for most mechanochemical reactions to be made (i) reactions induced by milling takes place in non-equilibrium conditions, whereby the final product retains the non-equilibrium state, that is, the stmcture is highly disordered, typically nanocrystalline or amorphous (ii) the kinetics and final products of the mechanically induced reactions depends on the milling conditions and (iii) in many instances crystallite size reduction preceeded phase transformation or chemical reaction. 

The great mechanical stresses and high temperatures that arise under conditions should be extremely favorable to the initiation and development of the entire complex of mechanochemical reactions. Thus, the properties of polymer masses reprocessed in various temperature mechanical systems should not coincide in principle, and different amounts of additives regulating the mechanochemical processes should be introduced into the polymer for the production of products with the same properties under different systems. 

Alternative methods such as coprecipitation or the sol-gel route were shown to favom the formation of ATLS already at temperatures around 800°C [37-40]. Mechanical milling of the mixture of source materials (oxides etc) in a planetary ball mill for several hours allows the production of ATLS even at room temperature [41-45]. However, such low-temperature methods have been successfully used only for the synthesis of undoped Lag 33Si6026, the data on the synthesis of the doped ATLS using mechanical milling are absent in the literature. It is well known that mechanochemical activation of the solids is a complex process, with different experimental parameters such as raw materials, type of the mill, rotation speed, ball-to-powder mass ratio, milling time etc. determining the formation of target products and a mechanism of their formation [46-47]. 

LAG is particularly interesting for mechanochemical synthesis of porous frameworks and inclusion compounds, as the liquid can sometimes become incorporated into the final product as a guest and so direct (template) its structure. One example of mechanochemical formation of a metal-organic host-guest complex is the kneading of copper(II) chloride and dace in the presence of A,A-dimethylsulfoxide (DMSO) or water, which leads to the simultaneous in situ formation of the 1-D coordination polymer host [Cu(dace)Cl2] and molecular inclusion to form inclusion compounds such as [Cu(dace)Cl2] DMSO (Figure 2b). Importantly, the polymeric host itself is not obtainable by neat grinding... 

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