Amphiphile solubility

The conditions for surfactants to be useful to form Hquid crystals exist when the cross-sectional areas of the polar group and the hydrocarbon chain are similar. This means that double-chain surfactants are eminently suited, and lecithin (qv) is a natural choice. Combiaations of a monochain ionic surfactant with a long-chain carboxyHc acid or alcohol yield lamellar Hquid crystals at low concentrations, but suffer the disadvantage of the alcohol being too soluble ia the oil phase. A combination of long-chain carboxyHc acid plus an amine of equal chain length suffers less from this problem because of extensive ionisa tion of both amphiphiles. 

Absorption is widely used as a raw material and/or product recovery technique in separation and purification of gaseous streams containing high concentrations of VOC, especially water-soluble compounds such as methanol, ethanol, isopropanol, butanol, acetone, and formaldehyde. Hydrophobic VOC can be absorbed using an amphiphilic block copolymer dissolved in water. However, as an emission control... 

Caiboxylate groups are hydrophilic ( water-loving ) and tend to confer water solubility on species that contain them. Long hydrocarbon chains are lipophilic ( fat-loving ) and tend to associate with other hydrocarbon chains. Sodium stearate is an exfflnple of an amphiphilic substance both hydrophilic and lipophilic groups occur within the sfflne molecule. 

The transformation of the hydrophobic periphery composed of bromo substituents into a hydrophilic wrapping of carboxylic acid functions was achieved by reacting 31 with (i) n-butyllithium and (ii) carbon dioxide. The polymer-analogous transformation provides water soluble, amphiphilic derivatives of 31 which constitute useful covalently bonded unimolecular models for micellar structures. 

The charged segments of the AMPS units in these amphiphilic copolymers effectively solubilize the sequences of hydrophobic monomer units to water. In fact, the copolymers ASt-72 (7 with x = 72), APh-50 (8 with x = 50), APy-50 (9 with x = 50), and ALa-44 (10 with x = 44) were all soluble in water. The copolymer ACh-x was a little less water soluble ACh-23 (11 with x = 23) was almost soluble, whereas ACh-60 was insoluble. All these copolymers were soluble in methanol, N, AT-dimethylformamide, and dimethylsulfoxide, but insoluble in most of other common organic solvents. 

ChEs present several amphiphilic and soluble homo-and hetero-oligomeric molecular forms in tissues and body fluids, with different tissue distributions (Fig. 1). 

A novel approach to RAFT emulsion polymerization has recently been reported.461529 In a first step, a water-soluble monomer (AA) was polymerized in the aqueous phase to a low degree of polymerization to form a macro RAFT agent. A hydrophobic monomer (BA) was then added under controlled feed to give amphiphilic oligomers that form micelles. These constitute a RAFT-containing seed. Continued controlled feed of hydrophobic monomer may be used to continue the emulsion polymerization. The process appears directly analogous to the self-stabilizing lattices approach previously used in macromonomer RAFT polymerization (Section 9.5.2). Both processes allow emulsion polymerization without added surfactant. 

Recently, unique vesicle-forming (spherical bUayers that offer a hydrophilic reservoir, suitable for incorporation of water-soluble molecules, as well as hydrophobic wall that protects the loaded molecules from the external solution) setf-assembUng peptide-based amphiphilic block copolymers that mimic biological membranes have attracted great interest as polymersomes or functional polymersomes due to their new and promising applications in dmg delivery and artificial cells [ 122]. However, in all the cases the block copolymers formed are chemically dispersed and are often contaminated with homopolymer. 

Van Bloois, L., Dekker, D. D., and Crommelin, D. J. A. (1987). Solubilization of lipophilic drugs by amphiphiles Improvement of the apparent solubility of almitrine bismesylate by liposomes, mixed micelles and O/W emulsions, Acta Pharmaceut. TechnoL,... 

In the case of amphiphilic molecules, characterized by the coexistence of spatially separated apolar (alkyl chains) and polar moieties, both parts cooperate to drive the intermolecular aggregation. This simple but pivotal peculiarity makes amphiphilic molecules soluble in both polar and apolar solvents and able to realize, in suitable conditions, an impressive variety of molecular aggregates characterized by spatially separated apolar and polar domains, local order at short times and fluidity at long times, and differences in size, shape (linear or branched chains, cyclic or globular aggregates, extended fractal-like molecular networks), and lifetime. 

In 2004, Weberskirch and co-workers tried a new approach by synthesising [RhBr(COD)(NHC)] 23 (NHC = l-(2 -hydroxyethyl)-3-methylimidazolidine-2-ylidene) [28]. Subsequently, attaching the unsymmetrical, monohydroxy-functionalised NHC by ester groups to an amphiphilic, water-soluble polymer support (ps)... 

As alternatives to amphiphilic betaines, a wide range of cationic, anionic, and non-ionic surfactants including environmentally benign sugar soaps have been successfully used as colloidal stabilizers [201]. Electrochemical reduction of the metal salts provides a very clean access to water soluble nanometal colloids [192]. 

The microgels could be conveniently isolated by precipitation as white powders, readily redispersable in many different organic solvents such as dialkylamides, nitriles, dichloromethane, acetone and THF. Further to this, the DMAA-based microgels exhibited a rather amphiphilic character and were also soluble in water and in alcohols such as methanol or ethanol in contrast, their counterparts based on MMA turned out to be more lipophilic and therefore insoluble in water and alcohols but soluble in organic solvents of low polarity such as toluene. 

Buhling et al. (1995) have used amphiphilic ligands in oxo-reactions, where with a pH swing the catalyst is made organic or water soluble (ligand Ph2Ar(P) with Ar = 3-hydroxy phenyl or 4- caroxy phenyl). 

Gulyas etal. (1997) have suggested new amphiphillic or water-soluble ligands. 

General anesthetics are usually small solutes with relatively simple molecular structure. As overviewed before, Meyer and Overton have proposed that the potency of general anesthetics correlates with their solubility in organic solvents (the Meyer-Overton theory) almost a century ago. On the other hand, local anesthetics widely used are positively charged amphiphiles in solution and reversibly block the nerve conduction. We expect that the partition of both general and local anesthetics into lipid bilayer membranes plays a key role in controlling the anesthetic potency. Bilayer interfaces are crucial for the delivery of the anesthetics. 

Local anesthetics are positively charged amphiphiles in solution. We have selected hydrochlorides of dibucaine (DBC H ), procaine (PRC H ), tetracaine (TTC H ), and lido-caine (LDC H ). All of these drugs are structurally similar they consist of the substituted benzene ring and tertiary amine moieties, as shown by (VI)-(IX) in Fig. 1. The presence of the positive charge increases the solubility in water and in consequence, the anesthetic efficiency. 

Surface active agents (surfactants) are active (adsorb) at surfaces and reduce surface tensions. Surfactants work because they are amphiphilic they have opposing solubility tendencies in one molecule, such as a hydrocarbon chain and a polar end. Because of this disparity in solubility, they tend to form concentration gradients at dissimilar phase interfaces. Surfactant additives are classified according to the interface at which they are active. 

Synthesis. The procedures used for the preparation of other amphiphilic networks (1) could not be used for the synthesis of PHEMA-1-PIB because of the insolubility of PHEMA in solvents that dissolve PIB e.g., THF. The above described silylation-desilylation procedure was designed to provide mutual solubility of the phases and thus to make the synthesis possible. 

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