Miscibility characteristics

Addition of co-solvents can also change the co-miscibility characteristics of ionic liquids. As an example, the hydrophobic [BMIM][PFg] salt can be completely dissolved in an aqueous ethanol mixture containing between 0.5 and 0.9 mole fraction of ethanol, whereas the ionic liquid itself is only partially miscible with pure water or pure ethanol [13]. The mixing of different salts can also result in systems with modified properties (e.g., conductivity, melting point). 

More or less similar behavior has been observed (8) in the blends of the copolymer or the terpolymer with the following bis-A polycarbonate, polyvinyl chloride, poly (ethyl methacrylate), and a terpolymer made from methyl methacrylate, N,N -dimethyl acrylamide, and N-phenyl-maleimide. Because of this unique miscibility characteristic of the a-methyl styrene interpolymers, an attempt was made at compati-bilizing polyarylethers with the interpolymers by attaching pendant chemical groups known to exist in systems with which the interpolymers are miscible. 

The blends of polysulfone with the a-methyl styrene polymers are immiscible, as evidenced by the double glass-transition temperatures in Table II. To improve the miscibility characteristics, polysulfone was modified in two ways. First, 25% of the bisphenol A was replaced by monomer I which contains a pendant ester group and, when no improvement resulted, the whole 50% of the bisphenol A was replaced. Again, the blends remain immiscible as evidenced from Figures 4 and 5 and from Table II. Further, the presence of the pendant ester group in polymer C does not improve the miscibility picture even though one would expect a favorable contribution from the carbonyl group on account of the miscibility of polycarbonate with the a-methyl styrene polymers. 

This work is an extension of our previous studies aimed at investigating miscibility characteristics of liquid crystal polymer systems. The present study has shown that it is possible to significantly modify the rheological properties of one liquid crystal polymer by blending with another liquid crystal polymer. 

The present study is part of a larger effort to understand the miscibility characteristics of semiflexible and rigid polymer systems. I4hat is emerging... 

This study was undertaken to develop techniques for direct monitoring of organic hydrothermal synthesis reactions in DACs combined with direct microscopic and spectroscopic observations. Such direct observation provided additional insight into the mechanism, kinetics and phase behavior (miscibility characteristics) of the fluid-rich system. Described below are some results on the direct monitoring of citric acid-HaO system at high P and T with DAC Raman spectroscopy combined with quench product gas chromatographic analysis. 

The acquisition of experimental liquid-hquid equUibria data for solvent-orgaitic mixtures of interest is invaluable for the screening of potential solvents for liquid-liquid extraction. The graphical representation of ternary Uquid-hquid equilibria is most suitably represented through the use of a triangular phase diagram (Fig. 1), where the miscibility characteristics of the system as a function of overall composition are shown. 

In the discussion above, the limited solubility of one polymer in another was ascribed to the unusually low entropy of mixing. In a block copolymer, cone chain portion is attached to another, end on end. It is interesting to note the miscibility characteristics and morphology of these materials. 

Sulfonation of PS has been found to cause moderate increases in the from 190°C to 210-225°C, and with the PBI-sulfonated PS miscible blend exhibiting excellent miscibility characteristics based on the hydrogen bonding between the N-H group of PBI and the sulfonated groups of the PS. Thermal stabihties at over 200°C were achievable, and the miscibility was found to be dependent on the PBI-sulfonated PS ratio as well as the degree of sulfonation. ... 

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