Solubility of Chains

Both phenomena make nevertheless the azo-modified chains more hydrophilic in presence of CDs (upper shift of LCSTs). The dark-adapted (trans) form is even 

CHAPTER ASSOCIATION BETWEEN AZOBENZENE MODIFIED POLYMERS 

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The model simulates an experimentally observed trend (25) that the solubility of chains in a SCF shows a strong inverse dependence on the molecular mass of the polymer. Figure 5 shows that changing the molecular weight of the chain molecule from 100 to 700 causes a reduction in solubility of nearly 6 orders of magnitude. The model also shows that all the solubility plots tend to flatten out around 300 bar, as observed in experiments (25). Classical EOS like a modified cubic EOS (2JD > when applied to such systems, produce solubility curves which tend to show a sharp maximum around 200 bar. For polymer-SCF systems, therefore, the lattice EOS is believed to be superior to modified cubic EOS. 

Frenkel, D, and Smit, B., Unexpected length dependence of the solubility of chain molecules. Mol. Phys. 75, 983 (1992). 

Figure 7.2. Photoswitch of the solubility of chains, (a) Schematic drawing of the phototriggered coiiapse and aggregation of azobenzene-containing polymers in poor soivent conditions or ciose to iow critical solubility temperature (LCST). (b) Typical variation of the radius of the chains as a function of solvent parameter, or temperature in the case of chains having a LCST in water. Bold line parent chain with no azobenzene dashed and dot-dashed lines azo-modified chains, respectively, exposed to UV and dark-adapted.

Table 79 gives a comparison with experimental data it records the measured and calculated solubilities of two higher hydrocarbons in decalin (mol. wt. = 138). The agreement is quite remarkable and supports the assumptions on which the theory is based w stands for the saturation concentration in weight per cent. It is evident from equation (75) how quickly the solubility of chain substances, on the basis of this theory, must decrease with increasing chain length, an effect which is entirely confirmed by experience. 

In polymer blends, such broadening is usually attributed to two possible mechanisms concentration fluctuation or intrinsic mobility differences between the blend components 28). Within the context of the system at hand, at some point of degradation, one can consider a blend of chains of lengths that are so diverse as to create microstructural heterogeneity, in part because the solubility of chains depends on molecular weight and the effect is more pronounced at low... 

Higher alcohols become more hydrocarbon like and less water soluble 1 Octanol for example dissolves to the extent of only 1 mL m 2000 mL of water As the alkyl chain gets longer the hydrophobic effect (Section 2 17) becomes more important to the point that It more than hydrogen bonding governs the solubility of alcohols... 

The acute toxicity of chlorinated paraffins to mammals, binds, and fish is very low (8), but over longer periods of exposure certain chlorinated paraffins have proved to be toxic to some aquatic species. However, the very low water solubility of chlorinated paraffins has made studies on aquatic species complicated. Laboratory experiments in which the chlorinated paraffins had been artificially solubilized showed only the short-chain grades to be toxic at low concentration other longer-chain grades showed no adverse effects on the majority of aquatic species tested. The degree of solubilization achieved in the laboratory is unlikely ever to be experienced in the environment and is of doubtful environmental relevance (9). 

The Michael addition reaction of amines and thiols with bismaleimides or functionalized monomaleimides is a versatile tool ia the synthesis of chain-extended maleimide-terroinated prepolymers. These prepolymers generally are soluble ia organic solvents from which they can be processed to prepreg and molded to high quaUty, void-free laminates. 

In contrast with 69, molecules of benzotelluradiazole 75 in the solid state are associated in dimers rather than polymeric chains. The bulky t-butyl groups of 75 prevent a higher degree of association and provide for good solubility of 75, which readily crystallizes from its pentane solution. 

Ionic liquids are similar to dipolar, aprotic solvents and short-chain alcohols in their solvent characteristics. These vary with anion (from very ionic Cl to more covalent [BETI] ). IFs become more lipophilic with increasing alkyl substitution, resulting in increasing solubility of hydrocarbons and non-polar organics. 

A wide variety of physical properties are important in the evaluation of ionic liquids (ILs) for potential use in industrial processes. These include pure component properties such as density, isothermal compressibility, volume expansivity, viscosity, heat capacity, and thermal conductivity. However, a wide variety of mixture properties are also important, the most vital of these being the phase behavior of ionic liquids with other compounds. Knowledge of the phase behavior of ionic liquids with gases, liquids, and solids is necessary to assess the feasibility of their use for reactions, separations, and materials processing. Even from the limited data currently available, it is clear that the cation, the substituents on the cation, and the anion can be chosen to enhance or suppress the solubility of ionic liquids in other compounds and the solubility of other compounds in the ionic liquids. For instance, an increase in allcyl chain length decreases the mutual solubility with water, but some anions ([BFJ , for example) can increase mutual solubility with water (compared to [PFg] , for instance) [1-3]. While many mixture properties and many types of phase behavior are important, we focus here on the solubility of gases in room temperature IFs. 

These core-shell type microspheres have very interesting structural features in that the cores are hardly crosslinked and the shell chains are fixed on the core surface with one end of the shell chains. The other end of the shell chains is free in good solvents for the shell chains. As the result of such a specific structure, the solubilities of the core-shell type polymer microspheres are governed by, not the core, but by the shell sequences, and the core-shell structures do not break even in the dilute solution [9,10]. 

The sulfonium precursor route may also be applied to alkoxy-substituted PPVs, but a dehydrohalogenation-condensation polymerization route, pioneered by Gilch, is favored 37]. The polymerization again proceeds via a quinomethide intermediate, but die syndicsis of the conjugated polymer requires only two steps and proceeds often in improved yields. The synthesis of the much-studied poly 2-methoxy-5-(2-ethylhexyloxy)-l,4-phenylene vinylene], MEH-PPV 15 is outlined in Scheme 1-5 33, 35]. The solubility of MEH-PPV is believed to be enhanced by the branched nature of its side-chain. 

The solubility of phthalocyanines in common organic solvents can be increased by introducing bulky or long-chain substituents either in the periphery of the macrocycle or, if the... 

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