Surface-active electrolytes, soluble

At the beginning of a batch reaction the continuous aqueous phase contains the water-soluble initiator, emulsifiers, and buffers. Common ionic emulsifiers will be present as molecularly dissolved electrolytes, as surface active agents at the various interfaces, and as molecular clusters called micelles. The monomer will be in three different locations. A small amount will be dissolved in the water phase. Some will be solublized within the emulsifier micelles. The bulk of the monomer, however, will exist in the relatively large (ca. 5 um) monomer droplets. Any oil-soluble components such as chain transfer agents will be distributed with the monomer if the water solubility is sufficient to permit transport from the droplets. 

The pressure history of the secondary alkaline flood reflects the formation of a secondary oil bank behind the immiscible phase oil bank. This secondary oil bank results in an overall recovery which is above that obtained by secondary waterflooding or by secondary caustic flooding with an univalent ion of high electrolyte concentration. The concentration history of the fractional water production during the secondary calcium hydroxide flood represents the total consumption of the hydroxyl ion. This consumption curve is made up of consumption due to adsorption of the silica surfaces and consumption due to the in situ chemical reaction which forms the more oil-soluble, surface-active salt, calcium oleate. 

Non-ionic surfactants do not exhibit Krafft points. Rather the solubility of non-ionic surfactants decreases with increasing temperature and the surfactants begin to lose their surface active properties above a transition temperature referred to as the cloud point. This occurs because above the cloud point, a separate surfactant rich phase of swollen micelles separates the transition is visible as a marked increase in dispersion turbidity. As a result, the foaming ability of, for example, polyoxyethylenated non-ionics decreases sharply above their cloud points. The addition of electrolyte usually lowers the cloud point while the addition of ionic surfactant usually increases the cloud points of their non-ionic counterparts, this increase being dependent on the composition of the mixed micelle. 

Contfary to electrolytes consisting of small ions that generally increase the surface tension of water, solutions of non-electrolytes tend to have surface tensions lower than that of water. Liquid non-electrolytes at ambient conditions, i.e., solvents that are immiscible with water but have a limited solubility in it, were already dealt with in Sect. 4.2. The surface tensions of aqueous organic solutes were reported in Adamson s book (Adamson 1990). The molecules of organic molecules tend to concentrate at the solution surface, they are surface active. 

FLUORAD Surfactant FC-100 is a general purpose amphoteric surfactant characterized by outstanding surface activity and solubility in aqueous solutions over a wide pH range. It is highly effective in solutions having a neutral pH, particularly those with a high electrolyte content. 

The compounds triisobutyl (methyl) phosphonium tosylate (a) and trihexyl (tetradecyl) phosphonium bis 2,4,4-(trimethylpentyl)phosphinate (b) were synthesized (Fig. 4.14), and their surface-active properties studied.The polar compound (a) is water soluble and surface active, does not form micelles, but affects the micelliza-tion properties of ionic, nonionic, and zwitterionic surfactants more strongly than conventional electrolytes. The less polar compound (b) forms micelles and has very low aqueous solubility. Both compounds form mixed micelles with Triton X-100 nonionic surfactant in aqueous solution. Compound (a) replaces water to form microemulsions with isopropyl myristate as oil, stabilized by (b). Compound (a) showed a clear antitumor activity, for example, 5mg (a)mH in 0.9% NaCl solution caused 100% killing of Sarcoma-180 cell line in 1 h. More diluted solutions were still active 2.5 and 1 mg (a) mT caused 81 and 53% killing of the same cells, respectively. On the other hand, compound (b) was less active than (a) lOmg (b)mT in 0.9% NaCl solution caused 89% killing of Sarcoma-180 cell line in 2h. Note that the concentration of (b) employed was 33 times higher than its cmc (0.03 x 10" moll ). The efficiency of (a) with respect to (b) may be due to the fact that the former does not form micellar aggregates [89]. 

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