Hydrophilic functional groups

AH corrosion inhibitors in use as of this writing are oil-soluble surfactants (qv) which consist of a hydrophobic hydrocarbon backbone and a hydrophilic functional group. Oil-soluble surfactant-type additives were first used in 1946 by the Sinclair Oil Co. (38). Most corrosion inhibitors are carboxyhc acids (qv), amines, or amine salts (39), depending on the types of water bottoms encountered in the whole distribution system. The wrong choice of inhibitors can lead to unwanted reactions. Eor instance, use of an acidic corrosion inhibitor when the water bottoms are caustic can result in the formation of insoluble salts that can plug filters in the distribution system or in customers vehicles. Because these additives form a strongly adsorbed impervious film at the metal Hquid interface, low Hquid concentrations are usually adequate. Concentrations typically range up to 5 ppm. In many situations, pipeline companies add their own corrosion inhibitors on top of that added by refiners. 

Liquid-Phase Components. It is usual to classify organic Hquids by the nature of the polar or hydrophilic functional group, ie, alcohol, acid, ester, phosphate, etc. Because lowering of surface tension is a key defoamer property and since this effect is a function of the nonpolar portion of the Hquid-phase component, it is preferable to classify by the hydrophobic, nonpolar portion. This approach identifies four Hquid phase component classes hydrocarbons, polyethers, siHcones, and duorocarbons. 

Fluorocarbons with a hydrophilic functional group are very active surfactants [23]. Less than 1% of ionic or nonionic surfactants with perfluoroalkyl groups can reduce the surface tension of water from 72 to 15-20 dyne/cm, compared with 25-35dyne/cm for typical hydrocarbon surfactants [24] Perfluoroether surfactants are about as active as their perfluoroalkyl counterparts of similar chain length [25, 26], but fluorosurfactants with more polar alkyl end groups are considerably less active than their perfluoroalkyl analogues (Table 7)... 

A wide range of polar, hydrophilic functional groups may be used to induce solubility in water, and these include sulfonates, alcohols, nitriles, amines,... 

Pristine CNTs are hydrophobic and cause a lack of solubility in biological aqueous fluids such as blood. The poor solubility of CNTs in blood stream poses a major challenge to in vivo studies making behavior of CNTs difficult to predict and control (Kam et al., 2005 Zheng et al., 2003a, b). Therefore, modification of CNT surface to introduce hydrophilic, functional groups has been utilized in pharmaceutical applications (Lacerda et al., 2006). However, insufficient in vivo evaluation of both pristine and surface-modified CNTs has been performed to answer essential questions on CNT toxicology. Additional in vivo studies also required to devise the best method of administration, means of uptake, metabolism, and elimination of CNTs. The in vivo studies on CNTs performed to date are presented in Table 12.2. 

The primer chosen for this investigation consisted of an equimolar mixture of phenyl- and amino-functional silanes, suggested as a potential superior primer for aluminum/epoxy adhesive joints [7], The amino-functional silane is known to be effective as an adhesion promoter for fiber-reinforced composite materials [1, 2] as well as for epoxy/metal adhesive joints [8, 9] and provides for strong chemical interaction between the adhesive and primer, while the phenyl functional silane should reduce the overall concentration of polar, hydrophilic functional groups in the interphase region and at the same time maintain or improve the ability of the resin and primer to interpenetrate due to its structural similarity to the adhesive resin. 

Adding polar functional groups to cross-linked, apolar polymeric resins by covalent chemical modification has developed particularly for generation of SPE sorbents suitable for recovery of polar compounds. Hydrophilic functional groups such as acetyl, benzoyl, o-carboxybenzoyl, 2-carboxy-3/4-nitrobenzoyl, 2,4-dicarboxybenzoyl, hydroxymethyl, sulfonate, trimethyl-ammonium, and tetrakis(/>-carboxyphenyl)porphyrin have been chemically... 

Synthetic detergents may have anionic, cationic, or nonionic hydrophilic functional groups. Of these detergents, only Gardol is a carboxylate salt and forms a precipitate in hard water. 

Surfactant foaming properties are related to surfactant chemical structure parameters such as hydrophobe size, ethylene oxide chain length, and hydrophile functional group. 

Oxidation tends to decrease lipophilicity by the introduction of hydrophilic functional groups forming metabolites that may be more readily excreted. In addition, many of these functionalized metabolites are also substrates for Phase II conjugation reactions. 

Micelles are colloidal particles formed by the concentration-dependent aggregation of surfactant molecules (1). In an aqueous environment micelles form when the hydrophobic portions of the surfactant molecules begin to associate at a surfactant concentration that is referred to as the "critical micelle concentration", or CMC, as a result of hydrophobic effects In water, a micelle has a hydrophobic core and a charged surface that is the result of the orientation of ionizable or hydrophilic functional groups out into the bulk solution At concentrations prior to the CMC the surfactant molecules migrate to the solution-air interface which disturbs the structure of the water molecules and results in a decrease in the solution s surface tension (2), At concentrations greater than the CMC, increasing... 

Many researchers have tried to prepare poly[n] catenane. However, all attempts have so far been unsuccessful. The first proposal for the preparation of poly[n]catenane was illustrated in the early 1970s [262-265]. Hydrocarbon terminated by hydrophilic functional groups was spread on the organic solvent-water interface. It was claimed that connection of the resulting U-shaped molecules by appropriate cyclic compounds followed by ring-closure afforded poly[n] catenane. However, no direct evidence for the poly[n] catenane structure was reported. A more sophisticated proposal based on the... 

---