Microstructured materials molecular approach

Since multiple electrical and optical functionality must be combined in the fabrication of an OLED, many workers have turned to the techniques of molecular self-assembly in order to optimize the microstructure of the materials used. In turn, such approaches necessitate the incorporation of additional chemical functionality into the molecules. For example, the successive dipping of a substrate into solutions of polyanion and polycation leads to the deposition of poly-ionic bilayers [59, 60]. Since the precursor form of PPV is cationic, this is a very appealing way to tailor its properties. Anionic polymers that have been studied include sulfonatcd polystyrene [59] and sulfonatcd polyanilinc 159, 60]. Thermal conversion of the precursor PPV then results in an electroluminescent blended polymer film. 

In literature, some researchers regarded that the continuum mechanic ceases to be valid to describe the lubrication behavior when clearance decreases down to such a limit. Reasons cited for the inadequacy of continuum methods applied to the lubrication confined between two solid walls in relative motion are that the problem is so complex that any theoretical approach is doomed to failure, and that the film is so thin, being inherently of molecular scale, that modeling the material as a continuum ceases to be valid. Due to the molecular orientation, the lubricant has an underlying microstructure. They turned to molecular dynamic simulation for help, from which macroscopic flow equations are drawn. This is also validated through molecular dynamic simulation by Hu et al. [6,7] and Mark et al. [8]. To date, experimental research had "got a little too far forward on its skis however, theoretical approaches have not had such rosy prospects as the experimental ones have. Theoretical modeling of the lubrication features associated with TFL is then urgently necessary. 

SOL-GEL TECHNOLOGY. The goal of sol-gel technology is lo use low temperature chemical processes to produce net-shape, net-surfacc objects, films, fibers, particulates, or composites that can be used commercially after a minimum of additional processing steps. See also Thin Films. Sol-gel processing can provide control of microstructures in the nanometer size range, i.e 1-100 nm (0.001-0.1 pm), which approaches the molecular level These materials often have unique physical and chemical characteristics. See also Nanotechnology (Molecular). 

The microstructure of epoxy thermosets can be complex, and both molecular and physical microstructures are presumed. Unfortunately, the intractable nature of these materials makes direct structural characterization extremely difficult. The most accessible technique for direct structural characterization is evaluation of epoxy rubber-like properties above Tg. Sometimes, indirect characterization of epoxy structure is possible due to the fact that the chemistry of several epoxy systems is well behaved (e.g., epoxy-amine chemistry). This permits epoxy network structure to be modeled accurately as a function of the extent of the crosslinking reaction(s). This approach has been developed extensively by Du ek and coworkers for amine-linked epoxies ... 

Pore structure analysis methods based upon realistic disordered microstructures may be classified into two types. In one approach, the experimental procedures used to fabricate the material are reproduced, to the greatest extent possible, via molecular simulation, and the resulting amorphous material structure is then statistically analyzed to obtain the desired structural information. In the other approach, adsorbent structural data (e.g., smaU-angle neutron scattering) is used to construct a model disordered porous structure that is statistically consistent with the experimental measurements. As in the first approach, molecular simulations can then be carried out using the derived model structure to obtain the structural characteristics of the original adsorbent. 

During the Stone Age, the material research was limited to the mechanical treatment of natural products. When Dalton discovered atomicity and Mendeleev revealed the periodic table, the research trends drastically changed in the intervening period and research was focussed on fundamental principles of basic molecular structure and simple chemical reactions. During the late twentieth century and the early twenty-first century, an exciting revolution in chemistry has taken place, with multidisciplinary approaches in nanoscience and nanotechnology to the creation of molecules with pre-specified complex structures to perform novel functions, hi the present century, research is focussed on control of crystal structures, nanostractures and microstructures with distinct mechanical, electrical, optical and magnetic properties [1-5]. 

Chemistry plays an important role in the fabrications of new functional materials with desired properties from conceptual point of view via tuning of microstructural properties. The synthetic approach of functional Inorganic nanomaterials with their novel properties and with their applications is a powerful driving force for the scientists in materials science. The synthesis of single source precursor was carried out based on molecular structure design concept (MSDC) for the stabilization via transformation into a solid crystalline nanostructure material with improved structural and properties. Single source precursor is a molecular entity which contains all the necessary elements of a final product in a well-defined structural formula [36-42]. It is of three types as shown below ... 

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