Phase behavior, -based copolymers

In the following, the phase behavior of copolymer-based blends will be illustrated by listing experimental results which have been published chiefly in the last five years. Phase behavior of homopolymer/copolymer and copolymer/copolymer Mends can be rationalized in temperature-copolymer composition and isothermal copolymer composition - copolymer composition plots, respectively, at fixed blend ratio. The blend systems will be classified as follows ... 

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. 

In conclusion, the mean-field theory outlined above turns out to be a powerful tool for rationalizing the complex phase behavior of polymer blends, especially of random copolymer based blends, in terms of interaction, ftee-volume and size effects. 

Random copolyesters based on bromoterephthalic acid, methyl hydroquinone, and hexane diol have been synthesized. Their mesophase properties were studied by differential scanning calorimetry, optical microscopy, realtime X-ray diffraction and melt rheology. At low molecular weight these copolymers exhibit triphasic behavior, where two mesomorphic phases coexist with an isotropic phase. Fractionation based on solubility in THF enables the identification of two components. Simple statistical arguments are employed to model the polymerization reaction and account for the observed phase behavior. 

Magerle, Krausch and coworkers showed based on AFM data and simulations that the phase behavior at interfaces [127] and in thin films (interphases) [128] can be understood in terms of analogous to those of classic, inorganic crystals. In Fig. 3.55 thin triblock copolymer films of SBS on silicon are shown, which display a rich variety of morphologies depending on the local film thickness [129]. 

This review discusses a newly proposed class of tempering Monte Carlo methods and their application to the study of complex fluids. The methods are based on a combination of the expanded grand canonical ensemble formalism (or simple tempering) and the multidimensional parallel tempering technique. We first introduce the method in the framework of a general ensemble. We then discuss a few implementations for specific systems, including primitive models of electrolytes, vapor-liquid and liquid-liquid phase behavior for homopolymers, copolymers, and blends of flexible and semiflexible... 

For those cases with weak to moderate specific interactions, a guide for assessing the miscibility and phase behavior of polymer blends is also presented based on classical thermodynamics utilizing a method of balancing the specific interactions and the negative dispersive forces [Coleman et al., 1990, 1991]. This approach successfully predicts the window of miscibility of copolymers with... 

Since, in most block copolymers, the first and second (or more) block segments are thermodynamically incompatible, an interesting morphological behavior based on molecular-level phase separation between the two blocks, followed by self-organization, is generally observed. Whilst the morphology of AB diblock copolymers has been widely studied and well established as Molar s rule, several... 

These calculations are a first step towards the prediction of the phase behavior of the three-component system water, ethanol and amphiphilic block copolymer. Hopefully, results based on this modeling approach can lead to a simplified synthesis and more precise tailoring of the structural features in meso-ordered thin films. 

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