Nonionic Amphiphiles

Of all the characteristic points in the phase diagram, the composition of the middle phase is most sensitive to temperature. Point M moves in an arc between the composition of the bottom phase (point B) at and the composition of the top phase (point T) at reaching its maximum surfactant concentration near T = - -T )/2. (Points B and Tmove by much smaller amounts, also.) The complete nonionic-amphiphile—oh—water—temperature... 

Fig. 3. Typical nonionic amphiphile—oil—water—temperature phase diagram, illustrating (a) the S-shaped curve of T, M, and B compositions, (b) the lines of plait points, (c) the lower and upper critical end points (at and respectively), and (d) the lower and upper critical tielines.

For nonionic amphiphiles, the effects of temperature on the phase behavior are large and the effects of inorganic electrolytes are very small. However, for ionic surfactants temperature effects are usually small, but effects of inorganic electrolytes are large. Most common electrolytes (eg, NaCl)... 

W. Brown, R. Johnsen, P. Stilbs, B. Lindman. Size and shape of nonionic amphiphile (Ci2Eg) micelles in dilute aqueous solutions as derived from quasielastic and intensity of light scattering, sedimentation and pulsed-field-gradient nuclear magnetic resonance self-diffusion data. J Phys Chem 87 4548-4553, 1983. 

Guerin, C. B. E. and Szleifer, I. (1999). Self-assembly of model nonionic amphiphilic molecules, Langmuir, 15, 7901-7911. 

Nonionic Amphiphilic Block Copolymers in Aqueous Solution. 89... 

Nonionic amphiphilic block copolymers in aqueous solution are typically formed of a water-soluble hydrophilic block, e.g., PEO, PMVE, PNIPAM, linked to a hydrophobic block, e.g., PPO, PBO, PS, PMMA. 

Bourrel M, Chambu C (1983) The Rules for Achieving High Solubilization of Brine and OU by AmphiphUic Molecules. Soc Petrol Eng J 23 327-338 Kunieda H, Shinoda K (1985) Evaluation of the hydrophile-lipophile balance (HLB) of nonionic surfactants I. Multisurfactant systems. J Colloid Interface Sci 107 107-121 Kahlweit M, Strey R, Eirman P (1986) Search for tricritical points in ternary systems Water-oil-nonionic amphiphile. J Phys Chem 90 671... 

M. Kahlweit and R. Strey. Phase-behavior of ternary-systems of the type H20-oil-nonionic amphiphile (microemulsions). Angewandte Chemie. International edition in English, 24(8) 654—668,1985. 

In the case of inverse systems, hydrophilic monomers such as hydroxyethyl acrylate, acrylamide, and acrylic acid were miniemulsified in non-polar media, e.g., cyclohexane or hexadecane [45,46]. Rather small and narrow distributed latexes in a size range between 50 nmsynthesized with nonionic amphiphilic block copolymers. Depending on the system, the surfactant loads can be as low as 1.5 wt% per monomer, which is very low for an inverse heterophase polymerization reaction and clearly underlines the advantages of the miniemulsion technique. 

Nonionic Amphiphilic Cyclodextrins Nonionic amphiphilic CDs are obtained by grafting aliphatic chains of different length on the primary and/or secondary face of the CD glucopyranose unit. Different derivatives depicted in Figure 5 are named after their structure ... 

FIGURE 5 Schematic representation of some nonionic amphiphilic CDs. 

Nonionic amphiphilic telechelic polymers consisting of polyethylene oxide with polyhedral oligosilsesquioxane, POSS, termini were prepared by Mather [3] and used as surfactants and thickening agents. The hydrophobicity of these amphiphilic telechelics, (III), was controlled by varying the molecular weight of the polyethylene oxide component. 

Mesoporous silica could also be prepared using nonionic amphiphilic surfactants with a polyethylene oxide... 

Some of the most widely used surfactant templates are nonionic amphiphilic triblock copolymers composed of poly(ethylene oxide)-poly(propylene oxide)-poly (ethylene oxide) blocks. These templates are nontoxic. 

It was also observed that nonionic amphiphilic ABA polymers (e.g., PEO-PPO-PEO) [200,205], polycations (e.g., quaternized poly(4-vinylpyridine) [214] and hydrophobically modified poly(N-isopropylacrylamide) [204] are able to accelerate translocation from the inside leaflet to the outside leaflet ( flip-flop ) within... 

The phase topography remains almost unchanged even if up to 75% of the ionic amphiphile is replaced by a nonionic amphiphile. 

Polyethylene oxide is not soluble in hydrocarbons such as hexane or decane. If a fatty chain is attached to a short segment of polyethylene oxide (4 to 8 ethylene oxide units), the nonionic amphiphile obtained exhibits a solubility profile in oil... 

The phase diagram of a nonionic amphiphile-water binary system is more complicated (see Figure 3.12). A classic upper critical point exists, but it is usually located below 0°C. At higher temperatures most nonionic amphiphiles show a miscibility gap, which is actually a closed loop with an upper as well as a lower critical point. The lower critical point CPp is often referred to as the cloud point temperature. The upper critical point often lies above the boiling temperature of the mixture (at 0.1 MPa). The position and the shape of the loop depend on... 

FIG. 3.12 Phase behavior of a water-nonionic amphiphile system (CP, critical point amph, amphiphile). 

FIG. 3.14 Binary phase diagram of a water-ethoxylated nonionic amphiphile system, including lyotropic liquid crystal domains. (From Kalhweit, M. and Strey, R., Angew. Chem. Int. Ed. Engl., 24, 654, 1985. With permission.)... 

Figure 3.15 shows some examples of real nonionic amphiphile-water binary phase diagrams [10,12], As a rule, amphiphiles with a hydrocarbon chain length of eight or fewer carbon atoms exhibit only the loop (in a domain depending on the ethoxylation) and no mesophase. 

FIG. 3.15 Examples of water-ethoxylated nonionic amphiphile binary phase diagrams. (FromBroze, G., Comm. J. Com. Esp. Deterg., Barcelona, 20, 133,1989. With permission.)... 

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