Energetic nanocomposites

In order to understand the thermodynamic issues associated with the nanocomposite formation, Vaia et al. have applied the mean-field statistical lattice model and found that conclusions based on the mean field theory agreed nicely with the experimental results [12,13]. The entropy loss associated with confinement of a polymer melt is not prohibited to nanocomposite formation because an entropy gain associated with the layer separation balances the entropy loss of polymer intercalation, resulting in a net entropy change near to zero. Thus, from the theoretical model, the outcome of nanocomposite formation via polymer melt intercalation depends on energetic factors, which may be determined from the surface energies of the polymer and OMLF. 

An equivalent surface area of 460 m g was determined from the monolayer volume, Vj. The value obtained for the dimensionless energetic constant, C=260, was characteristic of a microporous material. Although the BET surface area may not be a physically precise quantity due to the fact that the nitrogen molecule does not exhibit the same cross-sectional area in a microporous environment as on a flat surface, the BET value is useful for comparisons of relative porosities among a related class of adsorbents. For instance, smectite clays pillared by metal oxide aggregates typically exhibit BET surface areas in the range 150 - 400 m /g. Thus, the TSLS complex is among the more porous intercalated nanocomposites derived from smectite clays. 

Nanoparticles of iron and aluminum oxides and oxyhydroxides transport both organic and inorganic contaminants in the environment. The systematics developed here may be applied to understanding such natural nanocomposites. For example, it may be possible to treat coating of amorphous uranium or chromium oxides on nanophase (Fe, Al)OOH particles as a mixture of nanophase end-members from the point of view of energetics. 

Recent years there have been a considerable interest in studying of binary catalytic systems based on stabilized nanocomposites and amorphous alloys of copper with other metals. The reason is that the catalytic activity of such systems in many cases is sufficiently higher than that of individual metals. The most convenient model for theoretical description of binary systems characterized by the absence of far order is a cluster model. However, quantum-chemical study of binary clusters comprises the significantly more c omplicated problem than that o f individual metals, b ecause a correct theoretical description of metal-another metal cluster systems requires that the used method should be in a position to provide good results of calculations of geometrical, electron stmctures and energetic characteristics of both of individual metals. 

Another kind of nanocomposite is the energetic nanocomposite, generally as a hybrid sol-gel with a sihca base, which, when combined with metal oxides and nanoscale aluminum powder, can form superthermite materials [10,11]. 

A.E. Gash, Energetic nanocomposites with sol-gel chemistry Synthesis, safety, and characterization, LLNL UCRL-JC-146739, Retrieved 2008-09-28. K.R. Ryan, J.R. Gourley, and S.E. Jones, The Environmentalist, 29,56,2008. M. Evangelos, Nature Materials, 6,9,2007 Y. Mai, and Z. Yu, Polymer Nanocomposites, Woodhead Publ., 2006. 

On a thermodynamic ground, nanoscale mixing of layered silicates with polymers is only possible if the chemical structure of both components is such to grant favorable energetic interactions [4-8]. However, the morphology of experimental nanocomposites will be dependent on kinetics as well, and, consequently, on the pathway of their preparation. 

Oleg Borodin works as a scientist at the Electrochemistry Branch of the Army Research Laboratory, Adelphi, MD since 2011. After obtained a Ph.D. degree in Chemical Engineering in 2000 he worked in the area of multiscale modeling of liquid, ionic liquid and polymer electrolytes for battery and double layer capacitor applications, modeling of energetic composite materials, polymers in solutions, and polymer nanocomposites. He coauthored more than a hundred publications and four book chapters. His modeling efforts focus on the scales from electronic to atomistic and mesoscale. 

Misra, R., Fu, B.X., and Morgan, S.E. (2007) Surface energetics, dispersion, and nanotribomechanical behavior of POSS/PP hybrid nanocomposites. 

In order to put the topic of aerogel and sol-gel-derived energetic nanocomposites into the proper perspective, a short discussion of the classes and properties of energetic materials (EMs) is appropriate. Energetic materials are separated into three classes (1) explosives (2) propellants and (3) pyrotechnics [1]. Materials categorized this way are generally based... 

CudzUo S, Kicinski (2009) Preparation and characterization of energetic nanocomposites of organic gel -inorganic oxidizers. Propellants, Explosives, and Pyrotechnics 34 155-160. 

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