Critical solution temperature CST

These results show that the ligand (P(et-Rf8)3) has a very low leaching in perfluorohexane. Several fluorous solvents were tested for their critical solution temperature (CST) with the substrates (Table 5). 

A critical solution temperature (CST) is the minimum temperature for mixing of two substances in all proportions as liquid (Figure 1) or it is the maximum temperature of a binary system for two liquid phases in equilibrium. 

Schultz and Flory have developed, starting from the FH model and Equation 16.41, the following expression, which relates the critical solution temperature (CST), with the theta temperature and the polymer molecular weight ... 

Critical Solution Temperature (CST) of PETPP in Organic Solvents... 

Till now, there have been many studies on the solubility of nonaqueous solutions of ionic surfactants. On the other hand, information on nonionic surfactant solutions is still scarce. Kon-no et al. [27] studied the effect of temperature on the solubility of a-monoglycerol esters of Qi Q7 fatty acids in benzene. Such solubility behavior has also been observed by Matin and Pink [28] for zinc soaps in various organic solvents. The solubility increases slowly as the temperature is raised. Within a narrow temperature range, the solubility begins to increase very rapidly. The temperature at which the abrupt change in the solubility occurs is called the critical solution temperature (CST). 

It is well known that membranes of various kinds of phospholipids undergo phase transitions, such as a gel-to-liquid crystalline transition and a lamellar-to-hexagonal transition. These phase transitions have been used for the design of stimuli-sensitive liposomes. The, temperature sensitization of liposomes has been attempted using thermo-sensitive polymers that exhibit a lower critical solution temperature (CST). Attachment of these polymers to liposomes could give temperature-sensitive functionalities to the liposomes. ... 

On an empirical basis, solvents are given a number between zero and 32. Any solvent pair with a difierence of more than 17 has a Critical Solution Temperature (CST) of more than 75 C. For an M number difference of 16 the CST lies between 25 °C... 

The upper critical solution temperature (CST) is that temperature above which the two liquids become completely miscible in all proportions. Phenol-water system shows a lower CST. 

Another term, the critical solution temperature (CST), was introduced to designate the temperature beyond which the solubility of nonionic surfactants in organic solvents increases markedly, as marked by an inflection in the solubility curve. Mazer and Benedek used the critical micellar temperature (CMT) to refer to the phase boundary between a hydrated solid phase and a micellar phase." The CMT value was taken as the midpoint of the temperature range over which the hydrated solid phase clarified on slow warming with vigorous shaking. 

The mutual, although limited, solubility of perfluoroalkanoic and alkanoic acids suggests that their salts should be miscible in micelles, at least partially [71]. The nature and the number of different types of mixed micelles are still being debated [89,90]. However, at least some of the apparent incongruities are caused by differences in surfactant structure, composition of the solution, and temperature. The miscibility and critical solution temperature (cst) of binary systems depend on the chain length, the surfactant structures, and the composition of the solution. Above... 

The mutual miscibility of anionic fluorinated surfactants and hydrocarbon surfactants increases with increasing temperature, similar to the miscibility increase of fluorocarbon and hydrocarbon liquid mixtures [76,120]. In the LiFOS-LiTS system, the solubility of LiFOS increased substantially in the LiTS-rich micelle but only slightly in the LiFOS-rich micelle [99]. In comicellar systems, such as NF-STS [112] and LiFOS-LiDS [76], the temperature dependence of mutual miscibility exhibits a critical solution temperature (cst) that corresponds to the transition from two types of micelle to one type of mixed micelle. Above the cst, only one kind of mixed micelle exists below the critical solution temperature (cst), two types of micelles can coexist. 

The surfactants NFE and DE7 mix partially in micelles and their mutual solubility increases with increasing temperature. The mutual solubility of NFE and DEm in micelles is shown in Fig. 7.36. Above the critical solution temperature (cst) only one kind of mixed micelle exists, whereas below cst, two kinds of micelles can coexist, depending on the total concentration and chemical composition of the surfactants. The cst and the critical mole fraction of DEm in the NFE-DEm system decrease with increasing number, m, of oxyethylene units. The cst is... 

Aniline point is the mixing temperature of equal volumes of pure aniline and the other liquid, usually a hydrocarbon. The aniline point may be as much as 1° C. lower than the CST because the curve of mixing is unsymmetrical (Figure 1). Terms analogous to aniline point can be defined for other solvents—for example, furfural points. No distinction is made in the tables between critical solution temperatures and aniline points (or their analogs), because of the small difference mentioned. 

Fig. 4 General principle ofTPSC C, catalyst CST, critical solution temperature Org., organic solvent P, product S, substrate Temp., temperature.

The phase diagrams of polymer blends, the pseudo-binary polymer/polymer systems, are much scarcer. Furthermore, owing to the recognized difficulties in determination of the equilibrium properties, the diagrams are either partial, approximate, or built using low molecular weight polymers. Examples are fisted in Table 2.19. In the Table, CST stands for critical solution temperature — L indicates lower CST, U indicates upper CST (see Figure 2.15). 

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