Afoaming agent is a material such as asurfactant or ablowing agent that facilitates the formation offoam. A surfactant, when present in small amounts, reducessurface tension of a liquid (reduces the work needed to create the foam) or increases itscolloidal stability by inhibitingcoalescence of bubbles.[1] A blowing agent is a gas that forms the gaseous part of the foam.
Sodium laureth sulfate, or sodium lauryl ether sulfate (SLES), is adetergent andsurfactant found in many personal care products (soaps,shampoos,toothpastes, etc.). It is an inexpensive and effectivefoamer.Sodium lauryl sulfate (also known as sodium dodecyl sulfate orSDS) andammonium lauryl sulfate (ALS) are commonly used alternatives to SLES in consumer products.[2]
Surfactants which are less effective at foam production, may have additional co-surfactants added to increase foaming. In which case, the co-surfactant is referred to as the foaming agent. These are surfactants used in lower concentration in adetergent system than the primary surfactant, often thecocamide family of surfactants. Cocamide foaming agents include thenonioniccocamide DEA[3] andcocamidopropylamine oxide,[4] and thezwitterioniccocamidopropyl betaine andcocamidopropyl hydroxysultaine.[5]
There are two main types of blowing agents: gases at the temperature that the foam is formed, and gases generated by chemical reaction.Carbon dioxide,pentane, andchlorofluorocarbons are examples of the former. Blowing agents that produce gas via chemical reactions includebaking powder,azodicarbonamide,titanium hydride, andisocyanates (when they react with water).