Hydrophilic/lipophilic balance value

Alkylphenol ethoxylates (APEOs) are a class of surfactants that have been used widely in the drilling fluid industry. The popularity of these surfactants is based on their cost-effectiveness, availability, and range of obtainable hydrophilic-lipophilic balance values [693]. Studies have shown that APEOs exhibit oestrogenic effects and can cause sterility in some male aquatic species. This may have subsequent human consequences, and such problems have led to a banning of their use in some countries and agreements to phase out their use. Alternatives to products containing APEOs are available, and in some cases they show an even better technical performance. 

Lo Y-L (2003) Relationships between the hydrophilic-lipophilic balance values of pharmaceutical excipients and their multidrug resistance modulating effect in Caco-2 cells and rat intestines. J Control Release 90 37 -8... 

Effect of Hydrophile-Lipophile Balance Value on Digestibility... 

Becher and Becher (2) measured the spreading pressure, tt, of a series of surfactants on plant and synthetic surfaces. The surfactants were characterized by HLB (hydrophile-lipophile balance) values (3) similar to those of Jansen s adjuvants. The relationship between the spreading pressure and the contact angle can be expressed as tt = yL cos 0, where yL is the surface tension of the liquid and 6 is the contact angle between the liquid and a solid surface. Becher and Becher demonstrated that surfactants in their series which exhibited maximum spreading pres-... 

As well as the more common oil in water suspension methods, it is also possible to make stable water in oil suspensions by choosing alternative surfactants with much lower hydrophilic/lipophilic balance values, combined with solvents such as hydrocarbons as the dispersing phase. These can be used to make beaded polymers from water-soluble monomers such as acrylamide. Although little work has been done to date with imprinting in aqueous conditions (using hydrophobic interactions... 

The manner in which lecithin is modified to achieve increased hydrophilicity will greatly affect its emulsification properties. Different modifications will create lecithin products with different apparent HLB (hydrophile-lipophile balance) values, a term used to convey the approximate degree of water dispersibility (hydrophilicity) of lecithin products (31). The higher its HLB value, the more water dispersible the lecithin product. In o/w emulsions, the type of fat to be emulsified may require a specific type of hydrophilic lecithin for optimum emulsion stability. Dashiell (31) provides a short listing of fat types, and the corresponding class of lecithin found to give the most stable emulsion in model systems of water/fat/ emulsifier. 

EMSORB Ethoxylated Sorbltan Esters are the hydrophilic counterparts to the hydrophobic EMSORB Sorbltan Fatty Acid Esters. Varying moles of ethylene oxide are added to the Sorbltan Patty Acid Ester to produce these materials. The more ethylene oxide added the more hydrophilic the molecule becomes as seen by its increased Hydrophile-Lipophile balance Value (HLB). 

Greth and Wilson [100] successfully applied, in the emulsion polymerization of unsaturated monomers, a method of classifying emulsifiers based on the HLB (hydrophilic/lipophilic balance) value. They plotted the most important properties of the emulsion polymerization system, i.e., the latex stability, particle size, emulsion viscosity, and rate of polymerization against the HLB value of emulsifiers used. The dependence is described by a curve with maximum or minimum at a certain value of HLB, as it is expected from the micellar model [6, 7]. 

C for varying periods of time. Clearly the slope of decomposition is reduced as the pH is raised. The stability of hyper-molar urea solution is considerably increased by absorbing the solution into a polysaccharide particle. This particle can then be suspended in a continuous lipid phase with the correct incorporation of surfactants with a hydrophile/lipophile balance value suitable to maintain an aqueous-in lipid, continuous phase. The result of this is a compartmentalized system where the urea is in a more stabilized state and the polysaccharide has been altered in its hydrophobic/lipophilic properties to become what might be termed an ambiphilic matrix. 

Table 10.6 Hydrophilic-lipophilic balance values of modified lecithins...

---