Surfactants wetting properties

A central task for modern surfactant types in household and cosmetic use is good applicational behavior—foaming, wetting properties, hardness sensitivity, and so on—combined with reasonable dermatological properties. This chapter will give an overview about one of these the sulfosuccinates (Fig. 1). 

The effectiveness of surfactants in overcoming the hydrophobic effect of magnesium stearate may not be a result solely of an increase in the wetting properties of the bulk phase. Compared to putting the surfactant in the dosage form, Botzolakis [71] and Wang and Chowhan [135] found that adding an equivalent amount of surfactant to the dissolution medium was not effective. The possible impact of the surfactant at... 

Ananthapadmanabhan KP, Goddard ED, Chandar P (1990) A study of the solution, interfacial and wetting properties of silicone surfactants. Colloid Surf 44 281-297... 

Surfactant An adjuvant which improves the emulsifying, dispersing, spreading, and wetting properties of a pesticide. 

The wetting properties of the particles play a crucial role in flotation. We have already discussed the equilibrium position of a particle in the water-air interface (Section 7.2.2). The higher the contact angle the more stably a particle is attached to the bubble (Eq. 7.19) and the more likely it will be incorporated into the froth. Some minerals naturally have a hydrophobic surface and thus a high flotation efficiency. For other minerals surfactants are used to improve the separation. These are called collectors, which adsorb selectively on the mineral and render its surface hydrophobic. Activators support the collectors. Depressants reduce the collector s effect. Frothing agents increase the stability of the foam. 

The wetting properties of the trisiloxane surfactants will be discussed below. 

As supplied, PTFF dispersions contain nonionic wetting agent (surfactant), which provides them with good wetting properties and a minimum tendency to foam. Generally, nonionic surfactants are preferred because they are less likely to induce... 

Powerful nonionic surfactant combining excellent wetting properties with detergency and emulsifying ability over a broad range of pH and water hardness conditions. 

SURFACTANT 49 can be used as a preparation detergent or after dyeing clean up surfactant. Its high activity and excellent wetting properties allow for very low concentrations. Usually 0.25 to 0.50% OWG is all that is necessary. 

These sulfonates are still valued as anionic surfactants for consumer products. The secondary alkanesulfonates are known to have high solubility, fast wetting properties, chemical stability to alkali, acids, and strong oxidants such as chlorine. 

Polyglycol Ethers. Polyglycol ethers, produced by the reaction of fatty alcohol with ethylene oxide, constitute the most important class of nonionic surfactants. They possess good wetting properties, produce relatively low foam, and are highly effective at low temperature and low concentration. They are used as textile auxiliaries, in dishwashing liquids, degreasing products, and hquid cleaner formulations. 

Phosphate esters possess strong tolerance to electrolytes and alkalis. Their wetting properties are independent of the pH and, therefore, are used as surfactant components in both alkaline and acid cleaners (5). Their detergent properties are considered equal to nonionic surfactants, and they have excellent temperature stability. In their acid form, phosphate esters are moderately strong acids and, when neutralized to pH 5-8, have low order of toxicity. Phosphate esters are considered to be hydrotrope agents and are biodegradable. 

By using a recently developed magnesium hydride technology, the trisiloxane lyophobic part in superspreading surfactants can be substituted by a trimethylsilane moiety. This synthetic route leads to both nonionic and ionic silane surfactants, which are hydrolytically stable even under extreme pH. Aqueous solutions of these new surfactants exhibit surface tension and wetting properties comparable to the traditional organomodified trisiloxane surfactants. The combination of hydrolytic stability and biodegradability offers chance for the widespread application of these silane based surfactants. 

This may explain why short-chain surfactants with highly branched hydrophobic groups show such good wetting properties (see below). Since values of as are readily obtained (Chapter 2, Section IIIB), equation 6.23 can also be used to obtain relative diffusion coefficients from wetting times (Cohen, 1981). 

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