Mesoscale morphologies, in polymer

Mesoscale Morphologies in Polymer Blends Spherulites and Miorocrystallites... 

The effect of tacticity (i.e., the stereochemical arrangement of the units in the main chain of a polymer) on the properties of polymers and polymer blends has long been recognized with such basic differences as in the Tg, miscibility, crystallization, and blend characterization, including their mesoscale morphologies. In general, isotactic polymers (where all substituents are located on the same side of the polymer backbone) are semicrystalline in nature, whereas atactic polymers (where all substituents are placed randomly along the backbone) are amorphous. 

The prediction of the mesoscale morphology of complex polymer systems is very important for the final product properties. The application area of the proposed method includes computer simulation of such processes as emulsion copolymerization, copolymer melts and softened polymer melts, polymer blends, polymer surfactant stabilized emulsions, and adsorption phenomena in aqueous surfactant systems. 

To summarize, the crucial parameters that affect hole mobility include (1) the mesoscale morphology comprising the interconnectivity of crystalline domains and the presence of grain boundaries and (2) the <100> orientation distribution with respect to the substrate and, hence, the degree of in-plane a -stacking [67]. In the following section, studies on the orientation of the polymer chains with respect to the substrate are reviewed. 

Of course, nanocomposites are not the only area where mesoscale theories are being used to predict nanostructure and morphology. Other applications include—but are not limited to—block copolymer-based materials, surfactant and lipid liquid crystalline phases, micro-encapsulation of drugs and other actives, and phase behavior of polymer blends and solutions. In all these areas, mesoscale models are utilized to describe—qualitatively and often semi-quantitatively—how the structure of each component and the overall formulation influence the formation of the nanoscale morphology. 

Mesoscale crystalline morphology, crystallinity, and molecular orientation in these deposited thin films strongly depend on molecular properties [17,18], chemical nature of the solvent, and processing condition, resulting in very different field-effect mobilities [15,23,36]. Specifically, due to heterogeneous surface-induced (epitaxy) crystal growth as a nature of semicrystalline polymers, fine control of substrate properties and solvent evaporation rate tends to yield favorable molecular orientation of these polymers (i.e., edge-on structure with respect to dielectric substrates) in solution-deposited films [24,66]. 

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