Organics, solubility melting temperatures

The solubility of IL is strictly dependent on melting temperature of the solute, which is generally the result of the alkane or phenyl substituents at imidazolium ring. The conclusions can be taken from the solubilihes of benzimidazole and 2-phenylimidazole in water [94] and of every measured imidazoles in organic solvents [83-89]. 

This review article deals with aromatic polyimides that are processable from the melt or soluble in organic solvents. Conventional aromatic polyimides represent the most important family of heat resistant polymers, but they cannot be processed in the melt, and their application in the state of soluble intermediates always involves a hazardous step of cyclodehydration and elimination of a non-volatile polar solvent. A major effort has therefore been devoted to the development of novel soluble and/or melt-processable aromatic polyimides that can be applied in the state of full imidation. The structural factors conducive to better solubility and tractability are discussed, and representative examples of monomers showing favourable structural elements have been gathered and listed with the chemical criteria. Experimental and commercial aromatic polyimides are studied and evaluated by their solubility, transition temperatures and thermal resistance. An example is also given of the methods of computational chemistry applied to the study and design of polyimides with improved processability. 

A technique based on the formation of a multiple emulsion with an external aqueous phase was developed for the encapsulation of water-soluble drugs in order to replace the external oil phase. Possible unwanted interactions between the oil and the emulsified wax such as swelling or dissolution of the wax, clean-up requirements of the final product, and recovery of the oil phase could be eliminated. In analogy to the encapsulation of water-soluble drugs within polymeric microparticles by a w/o/w-solvent evaporation method, a molten wax phase was used instead of an organic polmer solution. A heated aqueous solution of pseudoephedrine HCl was emulsified into the molten carnauba wax, followed by the emulsification of this w/o-emulsion into a heated external aqueous phase. The temperature of the internal and external aqueous phases had to be kept above the melting temperature of the wax in order to avoid premature... 

TABLE 1.6 Melting Temperature, Enthalpy of Melting, and Ideal Solubility of Organic Solutes at 25 °C... 

Appearance Melting temperature (°C) Density (g/cc) Tensile strength [psi (N/m )l Solubility Crystallinity (%) Glass transition temperature (°C) Hard solid 175 0.90-0.92 5,000 (3.4X10 ) Insoluble in most organic solvents <70 0 to —35 Hard solid 131 0.89-0.91 Soluble in ether and aliphatic hydrocarbon Soft rubbery <100 0.86-0.89 Soluble in common organic solvents -11 to -35... 

High DS starch acetates are used to create brittle films and molded products. These have had little application, due to the economic superiority of cellulose acetates. In general, specific gravity and melting temperature both decrease with an increase in acetylation (45). Highly acetylated starches above 15% acetyl content (DS approximately 0.7) are soluble in water at 50° to 100°C and insoluble in organic solvents. When the acetyl content reaches 40% (DS approximately 2.5), the derivatized starch is soluble in aromatic hydrocarbons, ketones, and glycol ethers. 

Aromatic PAs are high-performance engineering thermoplastics with excellent mechaifical properties and thermal stability. However, they are difficult to process because of their limited solubility and high Tg or melt temperature. The research has been directed toward the synthesis of more tractable PAs, which are soluble in organic solvents. 

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